App crashes even when exceptions are handled

[Dnathan33]

Below is the implementation I am using for handling web socket requests.

WebSocketChannel.connect(Uri.parse(endpoint))

      final messageController = StreamController(onCancel: () {
        channel.sink.close();
      });

      channel.stream.listen(messageController.add, cancelOnError: true, onError: (e) {
        messageController.addError(e);
        channel.sink.close();
      });

When I purposefully use a wrong url. An exception is thown in the IOWebSocketChannel.connect function.

"Connection to '<URL>' was not upgraded to websocket"

Another Error

SocketException: Failed host lookup: 'URL' (OS Error: nodename nor servname provided, or not known, errno = 8)

The issue becomes that when these errors occur we handle these errors. However, even after the errors are handled the app still crashes.

[khomin]

Below is the implementation I am using for handling web socket requests.

WebSocketChannel.connect(Uri.parse(endpoint))

      final messageController = StreamController(onCancel: () {
        channel.sink.close();
      });

      channel.stream.listen(messageController.add, cancelOnError: true, onError: (e) {
        messageController.addError(e);
        channel.sink.close();
      });

When I purposefully use a wrong url. An exception is thown in the IOWebSocketChannel.connect function.

"Connection to '<URL>' was not upgraded to websocket"

Another Error

SocketException: Failed host lookup: 'URL' (OS Error: nodename nor servname provided, or not known, errno = 8)

The issue becomes that when these errors occur we handle these errors. However, even after the errors are handled the app still crashes.

Because the exceptions are inside the lib I've struggled a lot with that on desktop/web There are unhandled errors almost on every trivial case (like server is not responding) I came with idea to find another library or write my own

[leonardopivetta]

Same issue, using the WebSocketChannel.connect() method throws errors even if wrapped inside a try/catch block

[JadKHaddad]

Same issue, using the WebSocketChannel.connect() method throws errors even if wrapped inside a try/catch block

Same

[JadKHaddad]

WebSocketChannel channel = WebSocketChannel.connect(
    Uri.parse('ws://localhost:8000/ws'),
);

try {
    await channel.ready;
} catch (e) {
    print("Exception: $e");
}

[aimer63]

WebSocketChannel channel = WebSocketChannel.connect(
    Uri.parse('ws://localhost:8000/ws'),
);

try {
    await channel.ready;
} catch (e) {
    print("Exception: $e");
}

If the server is down this will print something like

 WebSocketChannelException: Instance of 'WebSocketException'

I didn't figure out how to extract more information about the exception, someone knows? Even doing this:

try {
  await _channel.ready;
} catch(e) {
  final we = e as WebSocketChannelException;
  final we1 = we.inner as WebSocketException;
  print('${we1.message}');
}

it spits :

Unhandled Exception: type 'WebSocketException' is not a subtype of type 'WebSocketException' in type cast where
  WebSocketException is from package:web_socket/src/web_socket.dart  
  WebSocketException is from dart:_http

What I'm missing?