The short of it is that _handle_ping_event() sometimes tries to send a reply to a closing socket, which raises an (avoidable) exception from within the websocket thread.
This can lead to unexpected MultiErrors crashing the app. That should be improved with python 3.11's ExceptionGroups, but still there's no reason for websockets to be throwing this particular exception while closing down a pipe.
Here is the exception:
Traceback (most recent call last):
File ".../python3.10/site-packages/trio_websocket/_impl.py", line 1205, in _reader_task
await handler(event)
File ".../python3.10/site-packages/trio_websocket/_impl.py", line 1145, in _handle_ping_event
await self._send(event.response())
File ".../python3.10/site-packages/trio_websocket/_impl.py", line 1249, in _send
data = self._wsproto.send(event)
File ".../python3.10/site-packages/wsproto/__init__.py", line 64, in send
data += self.connection.send(event)
File ".../python3.10/site-packages/wsproto/connection.py", line 107, in send
raise LocalProtocolError(
wsproto.utilities.LocalProtocolError: Event Pong(payload=bytearray(b'')) cannot be sent in state ConnectionState.LOCAL_CLOSING.
The short of it is that _handle_ping_event() sometimes tries to send a reply to a closing socket, which raises an (avoidable) exception from within the websocket thread.
This can lead to unexpected MultiErrors crashing the app. That should be improved with python 3.11's ExceptionGroups, but still there's no reason for websockets to be throwing this particular exception while closing down a pipe.
Here is the exception: