Don't render "Canceled" error (microsoft#249692)

We only get these now that cancellation is handled correctly for agent mode
Fix microsoft/vscode-copilot#17613

Author: roblourens

src/vs/base/common/errors.ts

@@ -192,7 +192,7 @@ export interface V8CallSite {
 	toString(): string;
 }
 
-const canceledName = 'Canceled';
+export const canceledName = 'Canceled';
 
 /**
  * Checks if the given error is a promise in canceled state

src/vs/workbench/contrib/chat/browser/chatListRenderer.ts

@@ -78,6 +78,7 @@ import { ChatMarkdownDecorationsRenderer } from './chatMarkdownDecorationsRender
 import { ChatMarkdownRenderer } from './chatMarkdownRenderer.js';
 import { ChatEditorOptions } from './chatOptions.js';
 import { ChatCodeBlockContentProvider, CodeBlockPart } from './codeBlockPart.js';
+import { canceledName } from '../../../../base/common/errors.js';
 
 const $ = dom.$;
 
@@ -537,7 +538,7 @@ export class ChatListItemRenderer extends Disposable implements ITreeRenderer<Ch
 			content.push({ kind: 'codeCitations', citations: element.codeCitations });
 		}
 
-		if (element.errorDetails?.message) {
+		if (element.errorDetails?.message && element.errorDetails.message !== canceledName) {
 			content.push({ kind: 'errorDetails', errorDetails: element.errorDetails, isLast: index === this.delegate.getListLength() - 1 });
 		}