fix: Add ESLint rules for type safety and fix violations

jest.config.js

@@ -4,13 +4,15 @@ const esModules = [
   '@codemirror',
   '@jupyter',
   '@microsoft',
+  '@deepnote',
   'exenv-es6',
   'lib0',
   'nanoid',
   'vscode-ws-jsonrpc',
   'y-protocols',
   'y-websocket',
-  'yjs'
+  'yjs',
+  'yaml'
 ].join('|');
 
 const baseConfig = jestJupyterLab(__dirname);

package.json

@@ -161,9 +161,12 @@
                     "args": "none"
                 }
             ],
-            "@typescript-eslint/no-explicit-any": "off",
+            "@typescript-eslint/no-explicit-any": "error",
             "@typescript-eslint/no-namespace": "off",
             "@typescript-eslint/no-use-before-define": "off",
+            "@typescript-eslint/no-floating-promises": "error",
+            "@typescript-eslint/no-non-null-assertion": "error",
+            "@typescript-eslint/prefer-nullish-coalescing": "error",
             "@typescript-eslint/quotes": [
                 "error",
                 "single",

src/__tests__/NotebookPicker.spec.ts

@@ -1,16 +1,37 @@
 // Copyright (c) Deepnote
 // Distributed under the terms of the Modified BSD License.
 
-import { NotebookPicker } from '../../src/components/NotebookPicker';
+import type { NotebookPanel } from '@jupyterlab/notebook';
 import { framePromise } from '@jupyterlab/testing';
-import { NotebookPanel } from '@jupyterlab/notebook';
-import { INotebookModel } from '@jupyterlab/notebook';
 import { Widget } from '@lumino/widgets';
 import { simulate } from 'simulate-event';
+import { NotebookPicker } from '../../src/components/NotebookPicker';
+
+// Mock types for testing
+interface MockNotebookModel {
+  fromJSON: jest.Mock;
+  cells: unknown[];
+  dirty: boolean;
+}
+
+interface MockNotebookPanel {
+  context: {
+    ready: Promise<void>;
+    model: {
+      getMetadata: jest.Mock;
+    };
+  };
+  model: MockNotebookModel | null;
+}
+
+// Type for widget with overridden protected method
+type WidgetWithMockOnAfterAttach = NotebookPicker & {
+  onAfterAttach: jest.Mock;
+};
 
 describe('NotebookPicker', () => {
-  let panel: NotebookPanel;
-  let model: INotebookModel;
+  let panel: MockNotebookPanel;
+  let model: MockNotebookModel;
 
   beforeEach(async () => {
     // Mock model + metadata
@@ -20,7 +41,7 @@ describe('NotebookPicker', () => {
         return [];
       },
       dirty: true
-    } as any;
+    };
 
     panel = {
       context: {
@@ -36,12 +57,14 @@ describe('NotebookPicker', () => {
         }
       },
       model
-    } as any;
+    };
 
     // Attach to DOM
-    const widget = new NotebookPicker(panel);
+    const widget = new NotebookPicker(
+      panel as unknown as NotebookPanel
+    ) as WidgetWithMockOnAfterAttach;
     // Override onAfterAttach to avoid errors from this.parent being null
-    (widget as any).onAfterAttach = jest.fn();
+    widget.onAfterAttach = jest.fn();
     Widget.attach(widget, document.body);
     await framePromise();
   });
@@ -56,7 +79,7 @@ describe('NotebookPicker', () => {
     const select = document.querySelector('select') as HTMLSelectElement;
     expect(select).not.toBeNull();
     expect(select.options.length).toBe(2);
-    expect(select.options[0] && select.options[0].value).toBe('nb1');
+    expect(select.options[0]?.value).toBe('nb1');
   });
 
   it('should call fromJSON when selecting a notebook', async () => {
@@ -98,14 +121,16 @@ describe('NotebookPicker', () => {
     getMetadata.mockReturnValue({ notebooks: {}, notebook_names: [] });
 
     document.body.innerHTML = '';
-    const widget = new NotebookPicker(panel);
+    const widget = new NotebookPicker(
+      panel as unknown as NotebookPanel
+    ) as WidgetWithMockOnAfterAttach;
     // Override onAfterAttach to avoid errors from this.parent being null
-    (widget as any).onAfterAttach = jest.fn();
+    widget.onAfterAttach = jest.fn();
     Widget.attach(widget, document.body);
     await framePromise();
 
     const select = document.querySelector('select') as HTMLSelectElement;
     expect(select.options.length).toBeGreaterThanOrEqual(1);
-    expect(select.options[0] && select.options[0].value).toBe('-');
+    expect(select.options[0]?.value).toBe('-');
   });
 });

src/components/NotebookPicker.tsx

@@ -12,18 +12,23 @@ export class NotebookPicker extends ReactWidget {
   constructor(private panel: NotebookPanel) {
     super();
 
-    void panel.context.ready.then(() => {
-      const deepnoteMetadata = this.panel.context.model.getMetadata('deepnote');
-      const metadataNames = deepnoteMetadata?.notebook_names;
-      const names =
-        Array.isArray(metadataNames) &&
-        metadataNames.every(n => typeof n === 'string')
-          ? metadataNames
-          : [];
+    panel.context.ready
+      .then(() => {
+        const deepnoteMetadata =
+          this.panel.context.model.getMetadata('deepnote');
+        const metadataNames = deepnoteMetadata?.notebook_names;
+        const names =
+          Array.isArray(metadataNames) &&
+          metadataNames.every(n => typeof n === 'string')
+            ? metadataNames
+            : [];
 
-      this.selected = names.length === 0 ? null : (names[0] ?? null);
-      this.update();
-    });
+        this.selected = names.length === 0 ? null : (names[0] ?? null);
+        this.update();
+      })
+      .catch(error => {
+        console.error('Failed to initialize NotebookPicker:', error);
+      });
   }
 
   private handleChange = (event: React.ChangeEvent<HTMLSelectElement>) => {
@@ -68,7 +73,9 @@ export class NotebookPicker extends ReactWidget {
   protected onAfterAttach(msg: Message): void {
     super.onAfterAttach(msg);
     requestAnimationFrame(() => {
-      MessageLoop.sendMessage(this.parent!, Widget.ResizeMessage.UnknownSize);
+      if (this.parent) {
+        MessageLoop.sendMessage(this.parent, Widget.ResizeMessage.UnknownSize);
+      }
     });
   }
 

src/handler.ts

@@ -25,21 +25,27 @@ export async function requestAPI(
   try {
     response = await ServerConnection.makeRequest(requestUrl, init, settings);
   } catch (error) {
-    throw new ServerConnection.NetworkError(error as any);
+    throw new ServerConnection.NetworkError(
+      error instanceof Error ? error : new Error(String(error))
+    );
   }
 
-  let data: any = await response.text();
+  let data: string | unknown = await response.text();
 
-  if (data.length > 0) {
+  if (typeof data === 'string' && data.length > 0) {
     try {
       data = JSON.parse(data);
-    } catch (error) {
+    } catch {
       console.log('Not a JSON response body.', response);
     }
   }
 
   if (!response.ok) {
-    throw new ServerConnection.ResponseError(response, data.message || data);
+    const errorMessage =
+      data && typeof data === 'object' && 'message' in data
+        ? (data as { message: string }).message
+        : String(data);
+    throw new ServerConnection.ResponseError(response, errorMessage);
   }
 
   return data;