extensions/typescript-language-features/src/tsServer/server.ts/ProcessBasedTsServer/tryCancelRequest
class ProcessBasedTsServer:	private tryCancelRequest(seq: number, command: string): boolean {
		try {
			if (this._requestQueue.tryDeletePendingRequest(seq)) {
				this.logTrace(`Canceled request with sequence number ${seq}`);
				return true;
			}

			if (this._requestCanceller.tryCancelOngoingRequest(seq)) {
				return true;
			}

			this.logTrace(`Tried to cancel request with sequence number ${seq}. But request got already delivered.`);
			return false;
		} finally {
			const callback = this.fetchCallback(seq);
			callback?.onSuccess(new ServerResponse.Cancelled(`Cancelled request ${seq} - ${command}`));
		}
	}