Marking arrays as readonly

extensions/typescript-language-features/src/features/bufferSyncSupport.ts

@@ -329,7 +329,7 @@ export default class BufferSyncSupport extends Disposable {
 
 	constructor(
 		client: ITypeScriptServiceClient,
-		modeIds: string[]
+		modeIds: readonly string[]
 	) {
 		super();
 		this.client = client;

extensions/typescript-language-features/src/typescriptServiceClient.ts

@@ -121,7 +121,7 @@ export default class TypeScriptServiceClient extends Disposable implements IType
 		private readonly onDidChangeTypeScriptVersion: (version: TypeScriptVersion) => void,
 		public readonly pluginManager: PluginManager,
 		private readonly logDirectoryProvider: LogDirectoryProvider,
-		allModeIds: string[]
+		allModeIds: readonly string[]
 	) {
 		super();
 		this.pathSeparator = path.sep;