fix test

Author: pwang347

src/platform/test/node/extensionContext.ts

@@ -64,6 +64,7 @@ function constructGlobalStoragePath(globalStoragePath: string): URI {
 export class MockExtensionContext implements BrandedService {
 	_serviceBrand = undefined;
 	extension = { id: 'GitHub.copilot-chat' } as any;
+	extensionUri = URI.from({ scheme: 'file', path: '/mock-extension' });
 	extensionMode = ExtensionMode.Test;
 	subscriptions = [];
 	globalStorageUri: Uri | undefined;