diff --git a/src/App.tsx b/src/App.tsx
index 6539682b..8671cc74 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -5,7 +5,6 @@ import {
   Button,
   ConfigProvider,
   Flex,
-  Input,
   message,
   Popconfirm,
   Space,
@@ -16,7 +15,6 @@ import {
   theme,
   Upload
 } from 'antd';
-import type { InputRef } from 'antd';
 import type { TreeDataNode, TreeProps } from 'antd';
 import type { UploadProps } from 'antd';
 import {
@@ -55,8 +53,6 @@ import * as editor from './editor/editor';
 import { extendedPythonGenerator } from './editor/extended_python_generator';
 import { createGeneratorContext, GeneratorContext } from './editor/generator_context';
 
-import * as toolboxItems from './toolbox/items';
-import * as toolbox from './toolbox/toolbox';
 //import { testAllBlocksInToolbox } from './toolbox/toolbox_tests';
 import ToolboxSettingsModal from './toolbox/settings';
 
@@ -173,6 +169,9 @@ const App: React.FC = () => {
   }, [storage]);
 
   const fetchMostRecentModulePath = async () => {
+    if (!storage) {
+      return;
+    }
     try {
       const value = await storage.fetchEntry('mostRecentModulePath', '');
       setMostRecentModulePath(value);
@@ -183,6 +182,9 @@ const App: React.FC = () => {
   };
 
   const initializeShownPythonToolboxCategories = async () => {
+    if (!storage) {
+      return;
+    }
     try {
       const value = await storage.fetchEntry('shownPythonToolboxCategories', '[]');
       const shownCategories: string[] = JSON.parse(value);
@@ -206,6 +208,10 @@ const App: React.FC = () => {
 
   const fetchListOfModules = async (): Promise<commonStorage.Project[]> => {
     return new Promise(async (resolve, reject) => {
+      if (!storage) {
+        reject(new Error());
+        return;
+      }
       try {
         const array = await storage.listModules();
         setModules(array)
@@ -348,7 +354,7 @@ const App: React.FC = () => {
     }
     if (currentModule && blocklyComponent.current && generatorContext.current) {
       const blocklyWorkspace = blocklyComponent.current.getBlocklyWorkspace();
-      setGeneratedCode(extendedPythonGenerator.workspaceToCode(
+      setGeneratedCode(extendedPythonGenerator.mrcWorkspaceToCode(
           blocklyWorkspace, generatorContext.current));
     } else {
       setGeneratedCode('');
@@ -462,6 +468,9 @@ const App: React.FC = () => {
   };
 
   const handleNewProjectNameOk = async (newProjectClassName: string) => {
+    if (!storage || !currentModule) {
+      return;
+    }
     const newProjectName = commonStorage.classNameToModuleName(newProjectClassName);
     const newProjectPath = commonStorage.makeProjectPath(newProjectName);
     if (newProjectNameModalPurpose === PURPOSE_NEW_PROJECT) {
@@ -553,7 +562,10 @@ const App: React.FC = () => {
   };
 
   const handleNewModuleNameOk = async (newModuleClassName: string) => {
-    const newModuleName = commonStorage.classNameToModuleName(newModuleClassName);
+    if (!storage || !currentModule) {
+    return;
+  }
+  const newModuleName = commonStorage.classNameToModuleName(newModuleClassName);
     const newModulePath = commonStorage.makeModulePath(currentModule.projectName, newModuleName);
     if (newModuleNameModalPurpose === PURPOSE_NEW_MECHANISM) {
       const mechanismContent = commonStorage.newMechanismContent(
@@ -612,26 +624,30 @@ const App: React.FC = () => {
   };
 
   const handleSaveClicked = async () => {
-    saveBlocks((success) => {});
+    saveBlocks();
   };
 
-  const saveBlocks = async (): boolean => {
-    if (blocksEditor.current && currentModulePath) {
+  const saveBlocks = async (): Promise<boolean> => {
+    return new Promise(async (resolve, reject) => {
+      if (!blocksEditor.current || !currentModulePath) {
+        reject(new Error());
+        return;
+      }
       try {
         await blocksEditor.current.saveBlocks();
         messageApi.open({
           type: 'success',
           content: 'Save completed successfully.',
         });
-        return true;
-      } catch (e: Error) {
+        resolve(true);
+      } catch (e) {
         console.log('Failed to save the blocks. Caught the following error...');
         console.log(e);
         setAlertErrorMessage('Failed to save the blocks.');
         setAlertErrorVisible(true);
+        reject(new Error('Failed to save the blocks.'));
       }
-    }
-    return false;
+    });
   };
 
   const handleRenameClicked = () => {
@@ -715,7 +731,7 @@ const App: React.FC = () => {
     afterPopconfirmOk.current = () => {
       setOpenPopconfirm(false);
       checkIfBlocksWereModified(async () => {
-        if (!currentModule) {
+        if (!storage || !currentModule) {
           return;
         }
         if (currentModule.moduleType == commonStorage.MODULE_TYPE_PROJECT) {
@@ -779,15 +795,20 @@ const App: React.FC = () => {
       }
       return isBlocks || Upload.LIST_IGNORE;
     },
-    onChange: (info) => {
-    },
     customRequest: ({ file, onSuccess, onError }) => {
+      if (!onSuccess || !onError) {
+        return;
+      }
+      const fileObject = file as File;
       const reader = new FileReader();
       reader.onload = async (event) => {
-        const dataUrl = event.target.result;
-        const uploadProjectName = commonStorage.makeUploadProjectName(file.name, getProjectNames());
+        const dataUrl = event.target?.result;
+        if (!storage || !dataUrl) {
+          return;
+        }
+        const uploadProjectName = commonStorage.makeUploadProjectName(fileObject.name, getProjectNames());
         try {
-          await storage.uploadProject(uploadProjectName, dataUrl);
+          await storage.uploadProject(uploadProjectName, dataUrl as string);
           onSuccess('Upload successful');
           await fetchListOfModules();
           const uploadProjectPath = commonStorage.makeProjectPath(uploadProjectName);
@@ -795,7 +816,7 @@ const App: React.FC = () => {
         } catch (e) {
           console.log('Failed to upload the project. Caught the following error...');
           console.log(e);
-          onError('Failed to upload the project.');
+          onError(new Error('Failed to upload the project.'));
           setAlertErrorMessage('Failed to upload the project');
           setAlertErrorVisible(true);
         }
@@ -803,16 +824,19 @@ const App: React.FC = () => {
       reader.onerror = (error) => {
         console.log('Failed to upload the project. reader.onerror called with the following error...');
         console.log(error);
-        onError('Failed to upload the project.');
+        onError(new Error('Failed to upload the project.'));
         setAlertErrorMessage('Failed to upload the project');
         setAlertErrorVisible(true);
       };
-      reader.readAsDataURL(file);
+      reader.readAsDataURL(fileObject);
     },
   };
 
   const handleDownloadClicked = () => {
     checkIfBlocksWereModified(async () => {
+      if (!storage || !currentModule) {
+        return;
+      }
       try {
         const url = await storage.downloadProject(currentModule.projectName);
         const link = document.createElement('a');
@@ -833,13 +857,16 @@ const App: React.FC = () => {
   };
 
   const handleToolboxSettingsOk = async (updatedShownCategories: Set<string>) => {
+    if (!storage) {
+      return;
+    }
     setShownPythonToolboxCategories(updatedShownCategories);
     const array = Array.from(updatedShownCategories);
     array.sort();
     storage.saveEntry('shownPythonToolboxCategories', JSON.stringify(array));
   };
 
-  const handleModuleSelected: TreeProps['onSelect'] = (a: React.Key[], e) => {
+  const handleModuleSelected: TreeProps['onSelect'] = (a: React.Key[]) => {
     if (a.length === 1) {
       checkIfBlocksWereModified(() => {
         setTreeSelectedKey(a[0]);
diff --git a/src/blocks/mrc_call_python_function.ts b/src/blocks/mrc_call_python_function.ts
index 185c4f9a..3d7b3fba 100644
--- a/src/blocks/mrc_call_python_function.ts
+++ b/src/blocks/mrc_call_python_function.ts
@@ -21,7 +21,7 @@
 
 
 import * as Blockly from 'blockly';
-import { Order, PythonGenerator } from 'blockly/python';
+import { Order } from 'blockly/python';
 
 import * as pythonUtils from './utils/generated/python';
 import { createFieldNonEditableText } from '../fields/FieldNonEditableText';
@@ -58,7 +58,7 @@ interface CallPythonFunctionMixin extends CallPythonFunctionMixinType {
   mrcImportModule: string,
   mrcActualFunctionName: string,
   mrcExportedFunction: boolean,
-  renameMethod(this: CallPythonFunctionBlock, oldName: string, newName: string): void;
+  renameMethod(this: CallPythonFunctionBlock, newName: string): void;
   mutateMethod(this: CallPythonFunctionBlock, defBlockExtraState: ClassMethodDefExtraState): void;
 }
 type CallPythonFunctionMixinType = typeof CALL_PYTHON_FUNCTION;
@@ -139,7 +139,7 @@ const CALL_PYTHON_FUNCTION = {
           break;
         }
         default:
-          throw new Error('mrcFunctionKind has unexpected value: ' + mrcFunctionKind)
+          throw new Error('mrcFunctionKind has unexpected value: ' + this.mrcFunctionKind)
       }
       const funcTooltip = this.mrcTooltip;
       if (funcTooltip) {
@@ -261,7 +261,7 @@ const CALL_PYTHON_FUNCTION = {
           break;
         }
         default:
-          throw new Error('mrcFunctionKind has unexpected value: ' + mrcFunctionKind)
+          throw new Error('mrcFunctionKind has unexpected value: ' + this.mrcFunctionKind)
       }
     }
 
@@ -305,7 +305,7 @@ const CALL_PYTHON_FUNCTION = {
     defBlockExtraState.params.forEach((param) => {
       this.mrcArgs.push({
         'name': param.name,
-        'type': param.type,
+        'type': param.type ?? '',
       });
     });
     this.updateBlock_();
@@ -345,7 +345,6 @@ export const pythonFromBlock = function(
       break;
     }
     case FunctionKind.CONSTRUCTOR: {
-      const callPythonFunctionBlock = block as CallPythonFunctionBlock;
       const className = block.getFieldValue(pythonUtils.FIELD_MODULE_OR_CLASS_NAME);
       code = className;
       break;
@@ -367,7 +366,7 @@ export const pythonFromBlock = function(
       break;
     }
     default:
-      throw new Error('mrcFunctionKind has unexpected value: ' + mrcFunctionKind)
+      throw new Error('mrcFunctionKind has unexpected value: ' + callPythonFunctionBlock.mrcFunctionKind)
   }
   code += '(' + generateCodeForArguments(callPythonFunctionBlock, generator, argStartIndex) + ')';
   if (block.outputConnection) {
diff --git a/src/blocks/mrc_class_method_def.ts b/src/blocks/mrc_class_method_def.ts
index 22c71943..e1a43d08 100644
--- a/src/blocks/mrc_class_method_def.ts
+++ b/src/blocks/mrc_class_method_def.ts
@@ -33,19 +33,12 @@ export const BLOCK_NAME = 'mrc_class_method_def';
 const MUTATOR_BLOCK_NAME = 'methods_mutatorarg';
 const PARAM_CONTAINER_BLOCK_NAME    = 'method_param_container';
 
-class MethodInput extends Blockly.inputs.Input {
-    readonly type = Blockly.inputs.inputTypes.CUSTOM;
-    constructor(name: string, block: Blockly.Block) {
-        super(name, block);
-    }
-}
-
 export type Parameter = {
     name: string,
     type?: string,
 };
 
-type ClassMethodDefBlock = Blockly.Block & ClassMethodDefMixin & Blockly.BlockSvg;
+export type ClassMethodDefBlock = Blockly.Block & ClassMethodDefMixin & Blockly.BlockSvg;
 interface ClassMethodDefMixin extends ClassMethodDefMixinType {
     mrcCanChangeSignature: boolean,
     mrcCanBeCalledWithinClass: boolean,
@@ -57,7 +50,7 @@ interface ClassMethodDefMixin extends ClassMethodDefMixinType {
 type ClassMethodDefMixinType = typeof CLASS_METHOD_DEF;
 
 /** Extra state for serialising call_python_* blocks. */
-type ClassMethodDefExtraState = {
+export type ClassMethodDefExtraState = {
     /**
      * Can change name and parameters and return type
      */
@@ -178,7 +171,7 @@ const CLASS_METHOD_DEF = {
 
         let paramBlock = containerBlock.getInputTargetBlock('STACK');
         while (paramBlock && !paramBlock.isInsertionMarker()) {
-            let param : Parameter = {
+            const param : Parameter = {
                 name : paramBlock.getFieldValue('NAME'),
                 type : ''
             }
@@ -192,13 +185,13 @@ const CLASS_METHOD_DEF = {
     decompose: function (this: ClassMethodDefBlock, workspace: Blockly.Workspace) {
         // This is a special sub-block that only gets created in the mutator UI.
         // It acts as our "top block"
-        let topBlock = workspace.newBlock(PARAM_CONTAINER_BLOCK_NAME);
+        const topBlock = workspace.newBlock(PARAM_CONTAINER_BLOCK_NAME);
         (topBlock as Blockly.BlockSvg).initSvg();
 
         // Then we add one sub-block for each item in the list.
-        var connection = topBlock!.getInput('STACK')!.connection;
+        let connection = topBlock!.getInput('STACK')!.connection;
 
-        for (var i = 0; i < this.mrcParameters.length; i++) {
+        for (let i = 0; i < this.mrcParameters.length; i++) {
             let itemBlock = workspace.newBlock(MUTATOR_BLOCK_NAME);
             (itemBlock as Blockly.BlockSvg).initSvg();
             itemBlock.setFieldValue(this.mrcParameters[i].name, 'NAME')
@@ -237,7 +230,7 @@ const CLASS_METHOD_DEF = {
 
       const legalName = findLegalMethodName(name, this);
       const oldName = nameField.getValue();
-      if (oldName !== name && oldName !== legalName) {
+      if (oldName && oldName !== name && oldName !== legalName) {
         // Rename any callers.
         renameMethodCallers(this.workspace, oldName, legalName);
       }
@@ -282,7 +275,7 @@ function findLegalMethodName(name: string, block: ClassMethodDefBlock): string {
  * @returns True if the name is used, otherwise return false.
  */
 function isMethodNameUsed(
-    name: string, workspace: Workspace, opt_exclude?: Block): boolean {
+    name: string, workspace: Blockly.Workspace, opt_exclude?: Blockly.Block): boolean {
   const nameLowerCase = name.toLowerCase();
   for (const block of workspace.getBlocksByType('mrc_class_method_def')) {
     if (block === opt_exclude) {
@@ -291,8 +284,9 @@ function isMethodNameUsed(
     if (nameLowerCase === block.getFieldValue('NAME').toLowerCase()) {
       return true;
     }
-    if (block.mrcPythonMethodName &&
-        nameLowerCase === block.mrcPythonMethodName.toLowerCase()) {
+    const classMethodDefBlock = block as ClassMethodDefBlock;
+    if (classMethodDefBlock.mrcPythonMethodName &&
+        nameLowerCase === classMethodDefBlock.mrcPythonMethodName.toLowerCase()) {
       return true;
     }
   }
@@ -315,11 +309,10 @@ interface MethodMutatorArgMixin extends MethodMutatorArgMixinType{
 type MethodMutatorArgMixinType = typeof METHODS_MUTATORARG;
 
 function setName(block: Blockly.BlockSvg){
-    let parentBlock = ChangeFramework.getParentOfType(block, PARAM_CONTAINER_BLOCK_NAME);
+    const parentBlock = ChangeFramework.getParentOfType(block, PARAM_CONTAINER_BLOCK_NAME);
     if (parentBlock) {
-        let done = false;
-        let variableBlocks = parentBlock!.getDescendants(true)
-        let otherNames: string[] = []
+        const variableBlocks = parentBlock!.getDescendants(true)
+        const otherNames: string[] = []
         variableBlocks?.forEach(function (variableBlock) {
             if (variableBlock != block) {
                 otherNames.push(variableBlock.getFieldValue('NAME'));
@@ -465,7 +458,7 @@ export const pythonFromBlock = function (
         xfix2 = xfix1;
     }
     if(block.mrcPythonMethodName == '__init__'){
-        branch = generator.defineClassVariables(block.workspace) + branch;
+        branch = generator.defineClassVariables() + branch;
     }    
     if (returnValue) {
         returnValue = generator.INDENT + 'return ' + returnValue + '\n';
diff --git a/src/blocks/mrc_get_python_enum_value.ts b/src/blocks/mrc_get_python_enum_value.ts
index 9dfa26d1..69fd8c06 100644
--- a/src/blocks/mrc_get_python_enum_value.ts
+++ b/src/blocks/mrc_get_python_enum_value.ts
@@ -21,7 +21,7 @@
 
 
 import * as Blockly from 'blockly';
-import { Order, PythonGenerator } from 'blockly/python';
+import { Order } from 'blockly/python';
 
 import * as pythonUtils from './utils/generated/python';
 import { createFieldDropdown } from '../fields/FieldDropdown';
diff --git a/src/blocks/mrc_get_python_variable.ts b/src/blocks/mrc_get_python_variable.ts
index 6f631feb..359e6e38 100644
--- a/src/blocks/mrc_get_python_variable.ts
+++ b/src/blocks/mrc_get_python_variable.ts
@@ -21,7 +21,7 @@
 
 
 import * as Blockly from 'blockly';
-import { Order, PythonGenerator } from 'blockly/python';
+import { Order } from 'blockly/python';
 
 import * as pythonUtils from './utils/generated/python';
 import { createFieldDropdown } from '../fields/FieldDropdown';
diff --git a/src/blocks/mrc_mechanism.ts b/src/blocks/mrc_mechanism.ts
index 2187a5aa..56d8c6ad 100644
--- a/src/blocks/mrc_mechanism.ts
+++ b/src/blocks/mrc_mechanism.ts
@@ -20,12 +20,12 @@
  * @author alan@porpoiseful.com (Alan Smith)
  */
 import * as Blockly from 'blockly';
-import { Order, PythonGenerator } from 'blockly/python';
+import { Order } from 'blockly/python';
 
 import { MRC_STYLE_FUNCTIONS } from '../themes/styles'
 import { createFieldNonEditableText } from '../fields/FieldNonEditableText';
 import { ExtendedPythonGenerator } from '../editor/extended_python_generator';
-import { getAllowedTypesForSetCheck, getOutputCheck } from './utils/python';
+import { getAllowedTypesForSetCheck } from './utils/python';
 
 export const BLOCK_NAME = 'mrc_mechanism';
 export const OUTPUT_NAME = 'mrc_mechansim';
diff --git a/src/blocks/mrc_misc_comment.ts b/src/blocks/mrc_misc_comment.ts
index fe480ce2..4d84d3aa 100644
--- a/src/blocks/mrc_misc_comment.ts
+++ b/src/blocks/mrc_misc_comment.ts
@@ -42,7 +42,7 @@ export const setup = function() {
 
 export const pythonFromBlock = function(
     block: Blockly.Block,
-    generator: PythonGenerator,
+    _: PythonGenerator,
 ) {
   return '# ' + block.getFieldValue('COMMENT') + '\n';
 };
diff --git a/src/blocks/mrc_set_python_variable.ts b/src/blocks/mrc_set_python_variable.ts
index 16724d38..87124f04 100644
--- a/src/blocks/mrc_set_python_variable.ts
+++ b/src/blocks/mrc_set_python_variable.ts
@@ -21,12 +21,12 @@
 
 
 import * as Blockly from 'blockly';
-import { Order, PythonGenerator } from 'blockly/python';
+import { Order } from 'blockly/python';
 
 import * as pythonUtils from './utils/generated/python';
 import { createFieldDropdown } from '../fields/FieldDropdown';
 import { createFieldNonEditableText } from '../fields/FieldNonEditableText';
-import { getAllowedTypesForSetCheck, getOutputCheck } from './utils/python';
+import { getAllowedTypesForSetCheck } from './utils/python';
 import { ExtendedPythonGenerator } from '../editor/extended_python_generator';
 import { MRC_STYLE_VARIABLES } from '../themes/styles';
 
diff --git a/src/editor/editor.ts b/src/editor/editor.ts
index 2d9ca141..6cc9994b 100644
--- a/src/editor/editor.ts
+++ b/src/editor/editor.ts
@@ -211,18 +211,24 @@ export class Editor {
   }
 
   private getModuleContent(): string {
-    const pythonCode = extendedPythonGenerator.workspaceToCode(this.blocklyWorkspace, this.generatorContext);
+    if (!this.currentModule) {
+      throw new Error('getModuleContent: this.currentModule is null.');
+    }
+    const pythonCode = extendedPythonGenerator.mrcWorkspaceToCode(
+        this.blocklyWorkspace, this.generatorContext);
     const exportedBlocks = JSON.stringify(this.generatorContext.getExportedBlocks());
-    const blocksContent = JSON.stringify(Blockly.serialization.workspaces.save(this.blocklyWorkspace));
-    return commonStorage.makeModuleContent(this.currentModule, pythonCode, exportedBlocks, blocksContent);
+    const blocksContent = JSON.stringify(
+        Blockly.serialization.workspaces.save(this.blocklyWorkspace));
+    return commonStorage.makeModuleContent(
+        this.currentModule, pythonCode, exportedBlocks, blocksContent);
   }
 
-  public async saveBlocks(): void {
+  public async saveBlocks() {
     const moduleContent = this.getModuleContent();
     try {
       await this.storage.saveModule(this.modulePath, moduleContent);
       this.moduleContent = moduleContent;
-    } catch (e: Error) {
+    } catch (e) {
       throw e;
     }
   }
diff --git a/src/editor/extended_python_generator.ts b/src/editor/extended_python_generator.ts
index daedb203..3780a7bc 100644
--- a/src/editor/extended_python_generator.ts
+++ b/src/editor/extended_python_generator.ts
@@ -59,23 +59,23 @@ export class ExtendedPythonGenerator extends PythonGenerator {
    * This is called from the python generator for the mrc_class_method_def for the
    * init method
    */
-  defineClassVariables(workspace: Blockly.Workspace) : string{
+  defineClassVariables() : string {
       let variableDefinitions = '';
 
-      if (this.context?.getHasMechanisms()){
+      if (this.context?.getHasMechanisms()) {
         variableDefinitions += this.INDENT + "self.mechanisms = []\n";
       }
       return variableDefinitions;
   }
-  getVariableName(nameOrId : string) : string{
-    const varName = super.getVariableName(name);
+  getVariableName(nameOrId: string): string {
+    const varName = super.getVariableName(nameOrId);
     return "self." + varName;
   }
   setHasMechanism() : void{
     this.context?.setHasMechanism();
   }
   
-  workspaceToCode(workspace: Blockly.Workspace, context: GeneratorContext): string {
+  mrcWorkspaceToCode(workspace: Blockly.Workspace, context: GeneratorContext): string {
     this.workspace = workspace;
     this.context = context;
     this.context.clear();
@@ -102,7 +102,7 @@ export class ExtendedPythonGenerator extends PythonGenerator {
   }
 
   finish(code: string): string {
-    if (this.context) {
+    if (this.context && this.workspace) {
       const className = this.context.getClassName();
       const classParent = this.context.getClassParent();
       this.addImport(classParent);
diff --git a/src/editor/generator_context.ts b/src/editor/generator_context.ts
index 6501a4d7..4532e2cb 100644
--- a/src/editor/generator_context.ts
+++ b/src/editor/generator_context.ts
@@ -55,26 +55,20 @@ export class GeneratorContext {
   }
 
   getClassName(): string {
+    if (!this.module) {
+      throw new Error('getClassName: this.module is null.');
+    }
     if (this.module.moduleType === commonStorage.MODULE_TYPE_PROJECT) {
       return 'Robot';
     }
 
-    // TODO(lizlooney): className should be a field in commonStorage.Module.
-    // Until that happens, we'll figure it out now from the module name.
-
-    let className = '';
-    let nextCharUpper = true;
-    for (let i = 0; i < this.module.moduleName.length; i++) {
-      const char = this.module.moduleName.charAt(i);
-      if (char !== '_') {
-        className += nextCharUpper ? char.toUpperCase() : char;
-      }
-      nextCharUpper = (char === '_');
-    }
-    return className;
+    return this.module.className;
   }
 
   getClassParent(): string {
+    if (!this.module) {
+      throw new Error('getClassParent: this.module is null.');
+    }
     if (this.module.moduleType === commonStorage.MODULE_TYPE_PROJECT) {
       return 'RobotBase';
     }
@@ -91,7 +85,7 @@ export class GeneratorContext {
     this.exportedBlocks.length = 0;
   }
 
-  setExportedBlocks(exportedBlocks: Blocks[]) {
+  setExportedBlocks(exportedBlocks: Block[]) {
     this.exportedBlocks.length = 0;
     this.exportedBlocks.push(...exportedBlocks);
   }
diff --git a/src/modal/NewModuleNameModal.tsx b/src/modal/NewModuleNameModal.tsx
index a4875faa..3b28bb33 100644
--- a/src/modal/NewModuleNameModal.tsx
+++ b/src/modal/NewModuleNameModal.tsx
@@ -83,7 +83,7 @@ export const NewModuleNameModal: React.FC<NewModuleNameModalProps> = ({ title, e
     }
   };
 
-  const onChange = (e) => {
+  const onChange = (e: React.ChangeEvent<HTMLInputElement>) => {
     setValue(commonStorage.onChangeClassName(e.target.value));
   };
 
diff --git a/src/modal/NewProjectNameModal.tsx b/src/modal/NewProjectNameModal.tsx
index 63335d07..3ee3f0dc 100644
--- a/src/modal/NewProjectNameModal.tsx
+++ b/src/modal/NewProjectNameModal.tsx
@@ -76,7 +76,7 @@ export const NewProjectNameModal: React.FC<NewProjectNameModalProps> = ({ title,
     }
   };
 
-  const onChange = (e) => {
+  const onChange = (e: React.ChangeEvent<HTMLInputElement>) => {
     setValue(commonStorage.onChangeClassName(e.target.value));
   };
 
diff --git a/src/storage/client_side_storage.ts b/src/storage/client_side_storage.ts
index 5a976462..d24a189a 100644
--- a/src/storage/client_side_storage.ts
+++ b/src/storage/client_side_storage.ts
@@ -28,15 +28,15 @@ const DATABASE_NAME = 'systemcore-blocks-interface';
 export async function openClientSideStorage(): Promise<commonStorage.Storage> {
   return new Promise((resolve, reject) => {
     const openRequest = window.indexedDB.open(DATABASE_NAME, 1);
-    openRequest.onerror = (event: Event) => {
+    openRequest.onerror = () => {
       console.log('IndexedDB open request failed. openRequest.error is...');
       console.log(openRequest.error);
       reject(new Error('IndexedDB open request failed.'));
     };
-    openRequest.onupgradeneeded = (event: Event) => {
+    openRequest.onupgradeneeded = () => {
       const db = openRequest.result;
 
-      var stores = db.objectStoreNames;
+      const stores = db.objectStoreNames;
 
       if (!stores.contains('entries')) {
         // Create an object store for key/value entries.
@@ -48,9 +48,9 @@ export async function openClientSideStorage(): Promise<commonStorage.Storage> {
         db.createObjectStore('modules', { keyPath: 'path' });
       }
     };
-    openRequest.onsuccess = (event: Event) => {
+    openRequest.onsuccess = () => {
       const db = openRequest.result;
-      resolve(new ClientSideStorage(db));
+      resolve(ClientSideStorage.create(db));
     };
   });
 }
@@ -58,6 +58,10 @@ export async function openClientSideStorage(): Promise<commonStorage.Storage> {
 class ClientSideStorage implements commonStorage.Storage {
   db: IDBDatabase;
 
+  static create(db: IDBDatabase) {
+    return new ClientSideStorage(db)
+  }
+
   private constructor(db: IDBDatabase) {
     this.db = db;
   }
@@ -65,7 +69,7 @@ class ClientSideStorage implements commonStorage.Storage {
   async saveEntry(entryKey: string, entryValue: string): Promise<void> {
     return new Promise((resolve, reject) => {
       const transaction = this.db.transaction(['entries'], 'readwrite');
-      transaction.oncomplete = (event: Event) => {
+      transaction.oncomplete = () => {
         resolve();
       };
       transaction.onabort = () => {
@@ -74,12 +78,12 @@ class ClientSideStorage implements commonStorage.Storage {
       };
       const entriesObjectStore = transaction.objectStore('entries');
       const getRequest = entriesObjectStore.get(entryKey);
-      getRequest.onerror = (event: Event) => {
+      getRequest.onerror = () => {
         console.log('IndexedDB get request failed. getRequest.error is...');
         console.log(getRequest.error);
         throw new Error('IndexedDB get request failed.');
       };
-      getRequest.onsuccess = (event: Event) => {
+      getRequest.onsuccess = () => {
         let value;
         if (getRequest.result === undefined) {
           value = Object.create(null);
@@ -89,7 +93,7 @@ class ClientSideStorage implements commonStorage.Storage {
         }
         value.value = entryValue;
         const putRequest = entriesObjectStore.put(value);
-        putRequest.onerror = (event: Event) => {
+        putRequest.onerror = () => {
           console.log('IndexedDB put request failed. putRequest.error is...');
           console.log(putRequest.error);
           throw new Error('IndexedDB put request failed.');
@@ -102,12 +106,12 @@ class ClientSideStorage implements commonStorage.Storage {
     return new Promise((resolve, reject) => {
       const getRequest = this.db.transaction(['entries'], 'readonly')
           .objectStore('entries').get(entryKey);
-      getRequest.onerror = (event: Event) => {
+      getRequest.onerror = () => {
         console.log('IndexedDB get request failed. getRequest.error is...');
         console.log(getRequest.error);
         reject(new Error('IndexedDB get request failed.'));
       };
-      getRequest.onsuccess = (event: Event) => {
+      getRequest.onsuccess = () => {
         const value = (getRequest.result === undefined) ? defaultValue : getRequest.result.value;
         resolve(value);
       };
@@ -124,12 +128,12 @@ class ClientSideStorage implements commonStorage.Storage {
       const openCursorRequest = this.db.transaction(['modules'], 'readonly')
           .objectStore('modules')
           .openCursor();
-      openCursorRequest.onerror = (event: Event) => {
+      openCursorRequest.onerror = () => {
         console.log('IndexedDB openCursor request failed. openCursorRequest.error is...');
         console.log(openCursorRequest.error);
         reject(new Error('IndexedDB openCursor request failed.'));
       };
-      openCursorRequest.onsuccess = (event: Event) => {
+      openCursorRequest.onsuccess = () => {
         const cursor = openCursorRequest.result;
         if (cursor) {
           const value = cursor.value;
@@ -214,12 +218,12 @@ class ClientSideStorage implements commonStorage.Storage {
     return new Promise((resolve, reject) => {
       const getRequest = this.db.transaction(['modules'], 'readonly')
           .objectStore('modules').get(modulePath);
-      getRequest.onerror = (event: Event) => {
+      getRequest.onerror = () => {
         console.log('IndexedDB get request failed. getRequest.error is...');
         console.log(getRequest.error);
         reject(new Error('IndexedDB get request failed.'));
       };
-      getRequest.onsuccess = (event: Event) => {
+      getRequest.onsuccess = () => {
         if (getRequest.result === undefined) {
           // Module does not exist.
           reject(new Error('IndexedDB get request succeeded, but the module does not exist.'));
@@ -244,7 +248,7 @@ class ClientSideStorage implements commonStorage.Storage {
     // When saving an existing module, the moduleType must be falsy.
     return new Promise((resolve, reject) => {
       const transaction = this.db.transaction(['modules'], 'readwrite');
-      transaction.oncomplete = (event: Event) => {
+      transaction.oncomplete = () => {
         resolve();
       };
       transaction.onabort = () => {
@@ -253,12 +257,12 @@ class ClientSideStorage implements commonStorage.Storage {
       };
       const modulesObjectStore = transaction.objectStore('modules');
       const getRequest = modulesObjectStore.get(modulePath);
-      getRequest.onerror = (event: Event) => {
+      getRequest.onerror = () => {
         console.log('IndexedDB get request failed. getRequest.error is...');
         console.log(getRequest.error);
         throw new Error('IndexedDB get request failed.');
       };
-      getRequest.onsuccess = (event: Event) => {
+      getRequest.onsuccess = () => {
         let value;
         if (getRequest.result === undefined) {
           // The module does not exist.
@@ -286,7 +290,7 @@ class ClientSideStorage implements commonStorage.Storage {
         value.content = moduleContent;
         value.dateModifiedMillis = Date.now();
         const putRequest = modulesObjectStore.put(value);
-        putRequest.onerror = (event: Event) => {
+        putRequest.onerror = () => {
           console.log('IndexedDB put request failed. putRequest.error is...');
           console.log(putRequest.error);
           throw new Error('IndexedDB put request failed.');
@@ -297,12 +301,8 @@ class ClientSideStorage implements commonStorage.Storage {
 
   private async _renameOrCopyProject(oldProjectName: string, newProjectName: string, copy: boolean): Promise<void> {
     return new Promise((resolve, reject) => {
-      const errorMessage = copy
-          ? 'Copy Project failed.'
-          : 'Rename Project failed.'
-
       const transaction = this.db.transaction(['modules'], 'readwrite');
-      transaction.oncomplete = (event: Event) => {
+      transaction.oncomplete = () => {
         resolve();
       };
       transaction.onabort = () => {
@@ -313,12 +313,12 @@ class ClientSideStorage implements commonStorage.Storage {
       // First get the list of modules in the project.
       const oldToNewModulePaths: {[key: string]: string} = {};
       const openCursorRequest = modulesObjectStore.openCursor();
-      openCursorRequest.onerror = (event: Event) => {
+      openCursorRequest.onerror = () => {
         console.log('IndexedDB openCursor request failed. openCursorRequest.error is...');
         console.log(openCursorRequest.error);
         throw new Error('IndexedDB openCursor request failed.');
       };
-      openCursorRequest.onsuccess = (event: Event) => {
+      openCursorRequest.onsuccess = () => {
         const cursor = openCursorRequest.result;
         if (cursor) {
           const value = cursor.value;
@@ -339,12 +339,12 @@ class ClientSideStorage implements commonStorage.Storage {
           // Now rename the project for each of the modules.
           Object.entries(oldToNewModulePaths).forEach(([oldModulePath, newModulePath]) => {
             const getRequest = modulesObjectStore.get(oldModulePath);
-            getRequest.onerror = (event: Event) => {
+            getRequest.onerror = () => {
               console.log('IndexedDB get request failed. getRequest.error is...');
               console.log(getRequest.error);
               throw new Error('IndexedDB get request failed.');
             };
-            getRequest.onsuccess = (event: Event) => {
+            getRequest.onsuccess = () => {
               if (getRequest.result === undefined) {
                 console.log('IndexedDB get request succeeded, but the module does not exist.');
                 throw new Error('IndexedDB get request succeeded, but the module does not exist.');
@@ -353,21 +353,19 @@ class ClientSideStorage implements commonStorage.Storage {
               value.path = newModulePath;
               value.dateModifiedMillis = Date.now();
               const putRequest = modulesObjectStore.put(value);
-              putRequest.onerror = (event: Event) => {
+              putRequest.onerror = () => {
                 console.log('IndexedDB put request failed. putRequest.error is...');
                 console.log(putRequest.error);
                 throw new Error('IndexedDB put request failed.');
               };
-              putRequest.onsuccess = (event: Event) => {
+              putRequest.onsuccess = () => {
                 if (!copy) {
                   const deleteRequest = modulesObjectStore.delete(oldModulePath);
-                  deleteRequest.onerror = (event: Event) => {
+                  deleteRequest.onerror = () => {
                     console.log('IndexedDB delete request failed. deleteRequest.error is...');
                     console.log(deleteRequest.error);
                     throw new Error('IndexedDB delete request failed.');
                   };
-                  deleteRequest.onsuccess = (event: Event) => {
-                  };
                 }
               };
             };
@@ -400,12 +398,8 @@ class ClientSideStorage implements commonStorage.Storage {
     }
 
     return new Promise((resolve, reject) => {
-      const errorMessage = copy
-          ? 'Copy module failed.'
-          : 'Rename module failed.'
-
       const transaction = this.db.transaction(['modules'], 'readwrite');
-      transaction.oncomplete = (event: Event) => {
+      transaction.oncomplete = () => {
         resolve();
       };
       transaction.onabort = () => {
@@ -416,12 +410,12 @@ class ClientSideStorage implements commonStorage.Storage {
       const oldModulePath = commonStorage.makeModulePath(projectName, oldModuleName);
       const newModulePath = commonStorage.makeModulePath(projectName, newModuleName);
       const getRequest = modulesObjectStore.get(oldModulePath);
-      getRequest.onerror = (event: Event) => {
+      getRequest.onerror = () => {
         console.log('IndexedDB get request failed. getRequest.error is...');
         console.log(getRequest.error);
         throw new Error('IndexedDB get request failed.');
       };
-      getRequest.onsuccess = (event: Event) => {
+      getRequest.onsuccess = () => {
         if (getRequest.result === undefined) {
           console.log('IndexedDB get request succeeded, but the module does not exist.');
           throw new Error('IndexedDB get request succeeded, but the module does not exist.');
@@ -431,20 +425,20 @@ class ClientSideStorage implements commonStorage.Storage {
         value.path = newModulePath;
         value.dateModifiedMillis = Date.now();
         const putRequest = modulesObjectStore.put(value);
-        putRequest.onerror = (event: Event) => {
+        putRequest.onerror = () => {
           console.log('IndexedDB put request failed. putRequest.error is...');
           console.log(putRequest.error);
           throw new Error('IndexedDB put request failed.');
         };
-        putRequest.onsuccess = (event: Event) => {
+        putRequest.onsuccess = () => {
           if (!copy) {
             const deleteRequest = modulesObjectStore.delete(oldModulePath);
-            deleteRequest.onerror = (event: Event) => {
+            deleteRequest.onerror = () => {
               console.log('IndexedDB delete request failed. deleteRequest.error is...');
               console.log(deleteRequest.error);
               throw new Error('IndexedDB delete request failed.');
             };
-            deleteRequest.onsuccess = (event: Event) => {
+            deleteRequest.onsuccess = () => {
             };
           }
         };
@@ -455,7 +449,7 @@ class ClientSideStorage implements commonStorage.Storage {
   private async _deleteProject(projectName: string): Promise<void> {
     return new Promise((resolve, reject) => {
       const transaction = this.db.transaction(['modules'], 'readwrite');
-      transaction.oncomplete = (event: Event) => {
+      transaction.oncomplete = () => {
         resolve();
       };
       transaction.onabort = () => {
@@ -466,12 +460,12 @@ class ClientSideStorage implements commonStorage.Storage {
       // First get the list of modulePaths in the project.
       const modulePaths: string[] = [];
       const openCursorRequest = modulesObjectStore.openCursor();
-      openCursorRequest.onerror = (event: Event) => {
+      openCursorRequest.onerror = () => {
         console.log('IndexedDB openCursor request failed. openCursorRequest.error is...');
         console.log(openCursorRequest.error);
         throw new Error('IndexedDB openCursor request failed.');
       };
-      openCursorRequest.onsuccess = (event: Event) => {
+      openCursorRequest.onsuccess = () => {
         const cursor = openCursorRequest.result;
         if (cursor) {
           const value = cursor.value;
@@ -484,12 +478,12 @@ class ClientSideStorage implements commonStorage.Storage {
           // Now delete each of the modules.
           modulePaths.forEach((modulePath) => {
             const deleteRequest = modulesObjectStore.delete(modulePath);
-            deleteRequest.onerror = (event: Event) => {
+            deleteRequest.onerror = () => {
               console.log('IndexedDB delete request failed. deleteRequest.error is...');
               console.log(deleteRequest.error);
               throw new Error('IndexedDB delete request failed.');
             };
-            deleteRequest.onsuccess = (event: Event) => {
+            deleteRequest.onsuccess = () => {
             };
           });
         }
@@ -505,7 +499,7 @@ class ClientSideStorage implements commonStorage.Storage {
 
     return new Promise((resolve, reject) => {
       const transaction = this.db.transaction(['modules'], 'readwrite');
-      transaction.oncomplete = (event: Event) => {
+      transaction.oncomplete = () => {
         resolve();
       };
       transaction.onabort = () => {
@@ -514,12 +508,12 @@ class ClientSideStorage implements commonStorage.Storage {
       };
       const modulesObjectStore = transaction.objectStore('modules');
       const deleteRequest = modulesObjectStore.delete(modulePath);
-      deleteRequest.onerror = (event: Event) => {
+      deleteRequest.onerror = () => {
         console.log('IndexedDB delete request failed. deleteRequest.error is...');
         console.log(deleteRequest.error);
         throw new Error('IndexedDB delete request failed.');
       };
-      deleteRequest.onsuccess = (event: Event) => {
+      deleteRequest.onsuccess = () => {
       };
     });
   }
@@ -531,12 +525,12 @@ class ClientSideStorage implements commonStorage.Storage {
       const openCursorRequest = this.db.transaction(['modules'], 'readonly')
           .objectStore('modules')
           .openCursor();
-      openCursorRequest.onerror = (event: Event) => {
+      openCursorRequest.onerror = () => {
         console.log('IndexedDB openCursor request failed. openCursorRequest.error is...');
         console.log(openCursorRequest.error);
         reject(new Error('IndexedDB openCursor request failed.'));
       };
-      openCursorRequest.onsuccess = async (event: Event) => {
+      openCursorRequest.onsuccess = async () => {
         const cursor = openCursorRequest.result;
         if (cursor) {
           const value = cursor.value;
@@ -571,7 +565,7 @@ class ClientSideStorage implements commonStorage.Storage {
   
       // Save each module.
       const transaction = this.db.transaction(['modules'], 'readwrite');
-      transaction.oncomplete = (event: Event) => {
+      transaction.oncomplete = () => {
         resolve();
       };
       transaction.onabort = () => {
@@ -585,12 +579,12 @@ class ClientSideStorage implements commonStorage.Storage {
         const moduleContent = moduleContents[moduleName];
         const modulePath = commonStorage.makeModulePath(projectName, moduleName);
         const getRequest = modulesObjectStore.get(modulePath);
-        getRequest.onerror = (event: Event) => {
+        getRequest.onerror = () => {
           console.log('IndexedDB get request failed. getRequest.error is...');
           console.log(getRequest.error);
           throw new Error('IndexedDB get request failed.');
         };
-        getRequest.onsuccess = (event: Event) => {
+        getRequest.onsuccess = () => {
           if (getRequest.result !== undefined) {
             // The module already exists. That is not expected!
             console.log('IndexedDB get request succeeded, but the module already exists.');
@@ -602,7 +596,7 @@ class ClientSideStorage implements commonStorage.Storage {
           value.content = moduleContent;
           value.dateModifiedMillis = Date.now();
           const putRequest = modulesObjectStore.put(value);
-          putRequest.onerror = (event: Event) => {
+          putRequest.onerror = () => {
             console.log('IndexedDB put request failed. putRequest.error is...');
             console.log(putRequest.error);
             throw new Error('IndexedDB put request failed.');
diff --git a/src/storage/common_storage.ts b/src/storage/common_storage.ts
index fa24bba8..f3acdfda 100644
--- a/src/storage/common_storage.ts
+++ b/src/storage/common_storage.ts
@@ -29,7 +29,7 @@ import startingMechanismBlocks from '../modules/mechanism_start.json';
 import startingRobotBlocks from '../modules/robot_start.json';
 
 import {extendedPythonGenerator} from '../editor/extended_python_generator';
-import { createGeneratorContext, GeneratorContext } from '../editor/generator_context';
+import { createGeneratorContext } from '../editor/generator_context';
 
 // Types, constants, and functions related to modules, regardless of where the modules are stored.
 
@@ -69,17 +69,17 @@ const NUMBER_OF_PARTS = 3;
 export const UPLOAD_DOWNLOAD_FILE_EXTENSION = '.blocks';
 
 export interface Storage {
-  async saveEntry(entryKey: string, entryValue: string): Promise<void>;
-  async fetchEntry(entryKey: string, defaultValue: string): Promise<string>;
-  async listModules(): Promise<Project[]>;
-  async fetchModuleContent(modulePath: string): Promise<string>;
-  async createModule(moduleType: string, modulePath: string, moduleContent: string): Promise<void>;
-  async saveModule(modulePath: string, moduleContent: string): Promise<void>;
-  async renameModule(moduleType: string, projectName: string, oldModuleName: string, newModuleName: string): Promise<void>;
-  async copyModule(moduleType: string, projectName: string, oldModuleName: string, newModuleName: string): Promise<void>;
-  async deleteModule(moduleType: string, modulePath: string): Promise<void>;
-  async downloadProject(projectName: string): Promise<string>;
-  async uploadProject(projectName: string, blobUrl: string): Promise<void>;
+  saveEntry(entryKey: string, entryValue: string): Promise<void>;
+  fetchEntry(entryKey: string, defaultValue: string): Promise<string>;
+  listModules(): Promise<Project[]>;
+  fetchModuleContent(modulePath: string): Promise<string>;
+  createModule(moduleType: string, modulePath: string, moduleContent: string): Promise<void>;
+  saveModule(modulePath: string, moduleContent: string): Promise<void>;
+  renameModule(moduleType: string, projectName: string, oldModuleName: string, newModuleName: string): Promise<void>;
+  copyModule(moduleType: string, projectName: string, oldModuleName: string, newModuleName: string): Promise<void>;
+  deleteModule(moduleType: string, modulePath: string): Promise<void>;
+  downloadProject(projectName: string): Promise<string>;
+  uploadProject(projectName: string, blobUrl: string): Promise<void>;
 }
 
 /**
@@ -151,7 +151,7 @@ export function isValidClassName(name: string): boolean {
 /**
  * Returns the module name for the given class name.
  */
-export function classNameToModuleName(className: string): boolean {
+export function classNameToModuleName(className: string): string {
   let moduleName = '';
   for (let i = 0; i < className.length; i++) {
     const char = className.charAt(i);
@@ -170,7 +170,7 @@ export function classNameToModuleName(className: string): boolean {
 /**
  * Returns the class name for the given module name.
  */
-export function moduleNameToClassName(moduleName: string): boolean {
+export function moduleNameToClassName(moduleName: string): string {
   let className = '';
   let nextCharUpper = true;
   for (let i = 0; i < moduleName.length; i++) {
@@ -241,7 +241,7 @@ function startingBlocksToModuleContent(
   const generatorContext = createGeneratorContext();
   generatorContext.setModule(module);
 
-  const pythonCode = extendedPythonGenerator.workspaceToCode(
+  const pythonCode = extendedPythonGenerator.mrcWorkspaceToCode(
       headlessBlocklyWorkspace, generatorContext);
   const exportedBlocks = JSON.stringify(generatorContext.getExportedBlocks());
   const blocksContent = JSON.stringify(
@@ -319,7 +319,7 @@ export function makeModuleContent(module: Module, pythonCode: string, exportedBl
       '"""\n');
 }
 
-function getParts(moduleContent: string): string {
+function getParts(moduleContent: string): string[] {
   // The last line is """.
   const lastChars = '\n"""\n';
   if (!moduleContent.endsWith(lastChars) || moduleContent.length <= lastChars.length) {
@@ -341,7 +341,10 @@ function getParts(moduleContent: string): string {
   // Ignore the first (index 0) element of the split array, which is the python
   // code.
   while (split.length > 1 && parts.length < NUMBER_OF_PARTS) {
-    parts.push(split.pop().trim());
+    const s = split.pop();
+    if (s) {
+      parts.push(s.trim());
+    }
   }
   if (parts.length < 2) {
     throw new Error('Unable to parse the module content.');
@@ -391,7 +394,7 @@ export function extractExportedBlocks(moduleName: string, moduleContent: string)
 /**
  * Extract the moduleType from the given module content.
  */
-export function extractModuleType(moduleName: string, moduleContent: string): Block[] {
+export function extractModuleType(moduleContent: string): string {
   const parts = getParts(moduleContent);
   let moduleType = parts[PARTS_INDEX_MODULE_TYPE];
   if (moduleType.startsWith(MARKER_MODULE_TYPE)) {
@@ -404,7 +407,7 @@ export function extractModuleType(moduleName: string, moduleContent: string): Bl
  * Produce the blob for downloading a project.
  */
 export async function produceDownloadProjectBlob(
-    projectName: string, moduleContents: {[key: string]: string}): string {
+    projectName: string, moduleContents: {[key: string]: string}): Promise<string> {
   const zip = new JSZip();
   for (let moduleName in moduleContents) {
     const moduleContent = moduleContents[moduleName];
@@ -457,7 +460,7 @@ export function makeUploadProjectName(
   let name = preferredName; // No suffix.
   let suffix = 0;
   while (true) {
-    var nameClash = false;
+    let nameClash = false;
     for (const existingProjectName of existingProjectNames) {
       if (name == existingProjectName) {
         nameClash = true;
@@ -477,7 +480,7 @@ export function makeUploadProjectName(
  */
 export async function processUploadedBlob(
     projectName: string, blobUrl: string)
-    : [{[key: string]: string}, {[key: string]: string}] {
+    : Promise<[{[key: string]: string}, {[key: string]: string}]> {
   const prefix = 'data:application/octet-stream;base64,';
   if (!blobUrl.startsWith(prefix)) {
     throw new Error('blobUrl does not have the expected prefix.');
@@ -485,9 +488,10 @@ export async function processUploadedBlob(
   const data = blobUrl.substring(prefix.length);
 
   const zip = await JSZip.loadAsync(data, {base64: true});
-  const promises = {};
+  const promises: {[key: string]: Promise<string>} = {};
   zip.forEach((moduleName, zipEntry) => {
     promises[moduleName] = zipEntry.async('text');
+    console.log("HeyLiz - promises[moduleName] is ..."); console.log(promises[moduleName]);
   });
 
   // Wait for all promises to resolve.
@@ -551,7 +555,7 @@ export function _processUploadedModule(
   const generatorContext = createGeneratorContext();
   generatorContext.setModule(module);
 
-  const pythonCode = extendedPythonGenerator.workspaceToCode(
+  const pythonCode = extendedPythonGenerator.mrcWorkspaceToCode(
       headlessBlocklyWorkspace, generatorContext);
   const exportedBlocks = JSON.stringify(generatorContext.getExportedBlocks());
   const moduleContent = makeModuleContent(
diff --git a/src/toolbox/items.ts b/src/toolbox/items.ts
index 3fefc2eb..47c3a4d8 100644
--- a/src/toolbox/items.ts
+++ b/src/toolbox/items.ts
@@ -31,6 +31,15 @@ export class Sep extends Item {
   }
 }
 
+export class Label extends Item {
+  text: string;
+
+  constructor(text: string) {
+    super('label');
+    this.text = text;
+  }
+}
+
 export class Block extends Item {
   /** The block type. */
   type: string;
@@ -53,7 +62,7 @@ export class Block extends Item {
   }
 }
 
-export type ContentsType = Sep | Block | Category;
+export type ContentsType = Sep | Label | Block | Category;
 
 export class Category extends Item  {
   /** The category name. */
diff --git a/src/toolbox/mechanism_class_methods.ts b/src/toolbox/mechanism_class_methods.ts
index 46146fbf..f556da93 100644
--- a/src/toolbox/mechanism_class_methods.ts
+++ b/src/toolbox/mechanism_class_methods.ts
@@ -19,7 +19,7 @@
  * @author lizlooney@google.com (Liz Looney)
  */
 
-import * as toolboxItems from '../toolbox/items';
+import * as toolboxItems from './items';
 
 
 /**
diff --git a/src/toolbox/methods_category.ts b/src/toolbox/methods_category.ts
index 4dec7fb3..d41ced35 100644
--- a/src/toolbox/methods_category.ts
+++ b/src/toolbox/methods_category.ts
@@ -21,11 +21,13 @@
 
 import * as Blockly from 'blockly/core';
 
+import * as toolboxItems from './items';
 import * as commonStorage from '../storage/common_storage';
 import { MRC_CATEGORY_STYLE_METHODS } from '../themes/styles'
 import { mechanism_class_blocks } from './mechanism_class_methods';
 import { opmode_class_blocks } from './opmode_class_methods';
 import { robot_class_blocks } from './robot_class_methods';
+import { ClassMethodDefBlock } from '../blocks/mrc_class_method_def'
 
 
 const CUSTOM_CATEGORY_METHODS = 'METHODS';
@@ -48,11 +50,8 @@ export class MethodsCategory {
     this.currentModule = currentModule;
   }
 
-  public methodsFlyout(workspace: Blockly.WorkspaceSvg): ToolboxInfo {
-    const toolboxInfo = {
-      contents: [
-      ],
-    }
+  public methodsFlyout(workspace: Blockly.WorkspaceSvg) {
+    const contents: toolboxItems.ContentsType[] = [];
 
     // Add blocks for defining any methods that can be defined in the current
     // module. For example, if the current module is an OpMode, add blocks to
@@ -61,7 +60,8 @@ export class MethodsCategory {
       // Collect the method names for mrc_class_method_def blocks that are
       // already in the blockly workspace.
       const methodNamesAlreadyUsed: string[] = [];
-      workspace.getBlocksByType('mrc_class_method_def', false).forEach((classMethodDefBlock) => {
+      workspace.getBlocksByType('mrc_class_method_def', false).forEach((block) => {
+        const classMethodDefBlock = block as ClassMethodDefBlock;
         if (!classMethodDefBlock.mrcCanChangeSignature) {
           methodNamesAlreadyUsed.push(classMethodDefBlock.getFieldValue('NAME'));
         }
@@ -71,22 +71,22 @@ export class MethodsCategory {
         // Add the methods for a Project (Robot).
         this.addClassBlocksForCurrentModule(
             'More Robot Methods', robot_class_blocks,
-            methodNamesAlreadyUsed, toolboxInfo.contents);
+            methodNamesAlreadyUsed, contents);
       } else if (this.currentModule.moduleType == commonStorage.MODULE_TYPE_MECHANISM) {
         // Add the methods for a Mechanism.
         this.addClassBlocksForCurrentModule(
             'More Mechanism Methods', mechanism_class_blocks,
-            methodNamesAlreadyUsed, toolboxInfo.contents);
+            methodNamesAlreadyUsed, contents);
       } else if (this.currentModule.moduleType == commonStorage.MODULE_TYPE_OPMODE) {
         // Add the methods for an OpMode.
         this.addClassBlocksForCurrentModule(
             'More OpMode Methods', opmode_class_blocks,
-            methodNamesAlreadyUsed, toolboxInfo.contents);
+            methodNamesAlreadyUsed, contents);
       }
     }
 
     // Add a block that lets the user define a new method.
-    toolboxInfo.contents.push(
+    contents.push(
       {
         kind: 'label',
         text: 'Custom Methods',
@@ -108,52 +108,61 @@ export class MethodsCategory {
     // For each mrc_class_method_def block in the blockly workspace, check if it
     // can be called from within the class, and if so, add a
     // mrc_call_python_function block.
-    workspace.getBlocksByType('mrc_class_method_def', false).forEach((classMethodDefBlock) => {
+    workspace.getBlocksByType('mrc_class_method_def', false).forEach((block) => {
+      const classMethodDefBlock = block as ClassMethodDefBlock;
       if (classMethodDefBlock.mrcCanBeCalledWithinClass) {
-        const callPythonFunctionBlock = {
+        const callPythonFunctionBlock: toolboxItems.Block = {
           kind: 'block',
           type: 'mrc_call_python_function',
-          importModule: '',
           extraState: {
             functionKind: 'instance_within',
             returnType: classMethodDefBlock.mrcReturnType,
             args: [],
+            importModule: '',
           },
           fields: {
             FUNC: classMethodDefBlock.getFieldValue('NAME'),
           },
         };
         classMethodDefBlock.mrcParameters.forEach((param) => {
-          callPythonFunctionBlock.extraState.args.push(
-            {
-              name: param.name,
-              type: param.type,
-            });
+          if (callPythonFunctionBlock.extraState) {
+            callPythonFunctionBlock.extraState.args.push(
+              {
+                name: param.name,
+                type: param.type ?? '',
+              });
+            }
           });
-        toolboxInfo.contents.push(callPythonFunctionBlock);
+        contents.push(callPythonFunctionBlock);
       }
     });
 
+    const toolboxInfo = {
+      contents: contents,
+    };
+
     return toolboxInfo;
   }
 
   private addClassBlocksForCurrentModule(
       label: string, class_blocks: toolboxItems.Block[],
-      methodNamesAlreadyUsed: string[], contents: []) {
+      methodNamesAlreadyUsed: string[], contents: toolboxItems.ContentsType[]) {
     let labelAdded = false;
     class_blocks.forEach((blockInfo) => {
-      const methodName = blockInfo.fields['NAME'];
-      if (!methodNamesAlreadyUsed.includes(methodName)) {
-        if (!labelAdded) {
-          contents.push(
-            {
-              kind: 'label',
-              text: label,
-            },
-          );
-          labelAdded = true;
+      if (blockInfo.fields) {
+        const methodName = blockInfo.fields['NAME'];
+        if (!methodNamesAlreadyUsed.includes(methodName)) {
+          if (!labelAdded) {
+            contents.push(
+              {
+                kind: 'label',
+                text: label,
+              },
+            );
+            labelAdded = true;
+          }
+          contents.push(blockInfo);
         }
-        contents.push(blockInfo);
       }
     });
   }
diff --git a/src/toolbox/opmode_class_methods.ts b/src/toolbox/opmode_class_methods.ts
index 195b7d21..068578f5 100644
--- a/src/toolbox/opmode_class_methods.ts
+++ b/src/toolbox/opmode_class_methods.ts
@@ -19,7 +19,7 @@
  * @author lizlooney@google.com (Liz Looney)
  */
 
-import * as toolboxItems from '../toolbox/items';
+import * as toolboxItems from './items';
 
 
 /**
diff --git a/src/toolbox/robot_class_methods.ts b/src/toolbox/robot_class_methods.ts
index 9b080fb1..d2b0d413 100644
--- a/src/toolbox/robot_class_methods.ts
+++ b/src/toolbox/robot_class_methods.ts
@@ -19,7 +19,7 @@
  * @author lizlooney@google.com (Liz Looney)
  */
 
-import * as toolboxItems from '../toolbox/items';
+import * as toolboxItems from './items';
 
 
 /**
diff --git a/src/toolbox/settings.tsx b/src/toolbox/settings.tsx
index 4c4c6b15..676a4d6e 100644
--- a/src/toolbox/settings.tsx
+++ b/src/toolbox/settings.tsx
@@ -3,7 +3,6 @@ import { Button, Flex, Modal, Splitter, Tree, Typography } from 'antd';
 import type { TreeDataNode, TreeProps } from 'antd';
 
 import * as toolboxItems from './items';
-import * as toolbox from './toolbox';
 import * as generatedToolbox from './generated/toolbox';
 
 
@@ -177,7 +176,7 @@ const ToolboxSettingsModal: React.FC<ToolboxSettingsModalProps> = ({ isOpen, sho
     }
   };
 
-  const handleModuleTreeSelected: TreeProps['onSelect'] = (a: React.Key[], e) => {
+  const handleModuleTreeSelected: TreeProps['onSelect'] = (a: React.Key[]) => {
     if (a.length === 1) {
       setModuleTreeSelectedKey(a[0]);
     }
diff --git a/src/toolbox/toolbox.ts b/src/toolbox/toolbox.ts
index 30281c88..9f261611 100644
--- a/src/toolbox/toolbox.ts
+++ b/src/toolbox/toolbox.ts
@@ -20,7 +20,7 @@
  */
 
 import * as generatedToolbox from './generated/toolbox';
-import * as toolboxItems from '../toolbox/items';
+import * as toolboxItems from './items';
 import {category as logicCategory} from './logic_category';
 import {category as loopCategory} from './loop_category';
 import {category as mathCategory} from './math_category';
diff --git a/src/toolbox/toolbox_tests.ts b/src/toolbox/toolbox_tests.ts
index 8ff9ca0c..5aa00f0d 100644
--- a/src/toolbox/toolbox_tests.ts
+++ b/src/toolbox/toolbox_tests.ts
@@ -21,7 +21,7 @@
 
 import * as Blockly from 'blockly/core';
 import { pythonGenerator } from 'blockly/python';
-import * as toolboxItems from '../toolbox/items';
+import * as toolboxItems from './items';
 
 
 // Tests