Fix sending message to terminated worker

src/vs/base/common/worker/workerClient.ts

@@ -227,7 +227,9 @@ export class WorkerClient {
 	}
 
 	private _postMessage(msg:any): void {
-		this._worker.postMessage(stringify(msg));
+		if (this._worker) {
+			this._worker.postMessage(stringify(msg));
+		}
 	}
 
 	private _onSerializedMessage(msg:string): void {

src/vs/base/worker/defaultWorkerFactory.ts

@@ -41,7 +41,9 @@ class WebWorker implements IWorker {
 	}
 
 	public postMessage(msg:string): void {
-		this.worker.postMessage(msg);
+		if (this.worker) {
+			this.worker.postMessage(msg);
+		}
 	}
 
 	public dispose(): void {