src/vs/base/common/worker/simpleWorker.ts/SimpleWorkerProtocol/_handleUnsubscribeEventMessage
class SimpleWorkerProtocol:	private _handleUnsubscribeEventMessage(msg: UnsubscribeEventMessage): void {
		if (!this._pendingEvents.has(msg.req)) {
			console.warn('Got unsubscribe for unknown req');
			return;
		}
		this._pendingEvents.get(msg.req)!.dispose();
		this._pendingEvents.delete(msg.req);
	}