Http Dart shelf_web_套接字和shelf_路由器出现劫持异常

我正在尝试实现一个基本服务器，它同时提供WebSocket和http请求

代码是这样的

import 'package:shelf_router/shelf_router.dart';
import 'package:shelf/shelf.dart';
import 'package:shelf/shelf_io.dart' as io;
import 'package:shelf_web_socket/shelf_web_socket.dart';

void main(List<String> args) async {
  var app = Router();

  var wsHandle = webSocketHandler((webSocket) {
    webSocket.stream.listen((message) {
      print(message);
      webSocket.sink.add("echo $message");
    });
  });

  app.get('/', (Request r) {
    return Response.ok('hello-world');
  });

  app.get("/ws", wsHandle);

  var server = await io.serve(app, 'localhost', 8080);
  print("Server is on at ${server.address.host} ${server.port}");
}

我找不到解决办法。这个解决方案对我不起作用

Exception has occurred.
HijackException (A shelf request's underlying data stream was hijacked.
This exception is used for control flow and should only be handled by a Shelf adapter.)