diff --git a/packages/common/src/errors.ts b/packages/common/src/errors.ts
index 3236fc5ed6..90ee2b4c81 100644
--- a/packages/common/src/errors.ts
+++ b/packages/common/src/errors.ts
@@ -9,10 +9,12 @@ export class UnsupportedLanguageError extends Error {
   }
 }
 
-export class UnsupportedError extends Error {
-  constructor(message: string) {
-    super(message);
-    this.name = "UnsupportedError";
+export class UnsupportedScopeError extends Error {
+  constructor(scopeType: string) {
+    super(
+      `Scope '${scopeType}' is not implemented yet; See ${DOCS_URL}/contributing/adding-a-new-scope`,
+    );
+    this.name = "UnsupportedScopeError";
   }
 }
 
diff --git a/packages/cursorless-engine/src/processTargets/modifiers/ContainingScopeStage.ts b/packages/cursorless-engine/src/processTargets/modifiers/ContainingScopeStage.ts
index fdbe17ab1b..23c23bf2f0 100644
--- a/packages/cursorless-engine/src/processTargets/modifiers/ContainingScopeStage.ts
+++ b/packages/cursorless-engine/src/processTargets/modifiers/ContainingScopeStage.ts
@@ -34,15 +34,11 @@ export class ContainingScopeStage implements ModifierStage {
   run(target: Target): Target[] {
     const { scopeType, ancestorIndex = 0 } = this.modifier;
 
-    const scopeHandler = this.scopeHandlerFactory.maybeCreate(
+    const scopeHandler = this.scopeHandlerFactory.create(
       scopeType,
       target.editor.document.languageId,
     );
 
-    if (scopeHandler == null) {
-      throw new NoContainingScopeError(scopeType.type);
-    }
-
     const containingScopes = getContainingScopeTarget(
       target,
       scopeHandler,
diff --git a/packages/cursorless-engine/src/processTargets/modifiers/EveryScopeStage.ts b/packages/cursorless-engine/src/processTargets/modifiers/EveryScopeStage.ts
index f9b3f43c43..6033a39001 100644
--- a/packages/cursorless-engine/src/processTargets/modifiers/EveryScopeStage.ts
+++ b/packages/cursorless-engine/src/processTargets/modifiers/EveryScopeStage.ts
@@ -42,15 +42,11 @@ export class EveryScopeStage implements ModifierStage {
     const { scopeType } = this.modifier;
     const { editor, isReversed } = target;
 
-    const scopeHandler = this.scopeHandlerFactory.maybeCreate(
+    const scopeHandler = this.scopeHandlerFactory.create(
       scopeType,
       editor.document.languageId,
     );
 
-    if (scopeHandler == null) {
-      throw new NoContainingScopeError(scopeType.type);
-    }
-
     let scopes: TargetScope[] | undefined;
 
     if (target.hasExplicitRange) {
@@ -97,15 +93,11 @@ export class EveryScopeStage implements ModifierStage {
     scopeHandlerFactory: ScopeHandlerFactory,
     target: Target,
   ): Range[] {
-    const iterationScopeHandler = scopeHandlerFactory.maybeCreate(
+    const iterationScopeHandler = scopeHandlerFactory.create(
       scopeHandler.iterationScopeType,
       target.editor.document.languageId,
     );
 
-    if (iterationScopeHandler == null) {
-      throw Error("Could not find iteration scope handler");
-    }
-
     const iterationScopeTarget = getContainingScopeTarget(
       target,
       iterationScopeHandler,
diff --git a/packages/cursorless-engine/src/processTargets/modifiers/scopeHandlers/ScopeHandlerFactoryImpl.ts b/packages/cursorless-engine/src/processTargets/modifiers/scopeHandlers/ScopeHandlerFactoryImpl.ts
index 4002f883fe..b23314d897 100644
--- a/packages/cursorless-engine/src/processTargets/modifiers/scopeHandlers/ScopeHandlerFactoryImpl.ts
+++ b/packages/cursorless-engine/src/processTargets/modifiers/scopeHandlers/ScopeHandlerFactoryImpl.ts
@@ -1,4 +1,8 @@
-import { pseudoScopes, type ScopeType } from "@cursorless/common";
+import {
+  pseudoScopes,
+  UnsupportedScopeError,
+  type ScopeType,
+} from "@cursorless/common";
 import type { LanguageDefinitions } from "../../../languages/LanguageDefinitions";
 import {
   BoundedNonWhitespaceSequenceScopeHandler,
@@ -145,7 +149,7 @@ export class ScopeHandlerFactoryImpl implements ScopeHandlerFactory {
   ): ScopeHandler {
     const handler = this.maybeCreate(scopeType, languageId);
     if (handler == null) {
-      throw new Error(`Couldn't create scope handler for '${scopeType.type}'`);
+      throw new UnsupportedScopeError(scopeType.type);
     }
     return handler;
   }