OSError observed in logs with example using latest version of socket.io library.

[jgerry2002]

Describe the bug
Using the latest version of socket.io javascript libraries in template we are seeing a client disconnect error similar to miguelgrinberg/Flask-SocketIO#377

To Reproduce
Steps to reproduce the behavior:

1. Go to example
2. Open index.html template
3. Replace socket.io 3.0.4 with 4.7.2
4. OSError observed in logs

Expected behavior
A clean disconnect without raising an OSErorr

Logs
Client disconnected FP-tnyVJscQNJp0LAAAC
Traceback (most recent call last):
File "/opt/miguel-env/lib64/python3.9/site-packages/flask/app.py", line 2552, in call
return self.wsgi_app(environ, start_response)
File "/opt/miguel-env/lib64/python3.9/site-packages/flask_socketio/init.py", line 43, in call
return super(_SocketIOMiddleware, self).call(environ,
File "/opt/miguel-env/lib64/python3.9/site-packages/engineio/middleware.py", line 63, in call
return self.engineio_app.handle_request(environ, start_response)
File "/opt/miguel-env/lib64/python3.9/site-packages/socketio/server.py", line 428, in handle_request
return self.eio.handle_request(environ, start_response)
File "/opt/miguel-env/lib64/python3.9/site-packages/engineio/server.py", line 321, in handle_request
start_response(r['status'], r['headers'] + cors_headers)
OSError: headers already sent

Additional context
use default suggested uwsgi configuration: uwsgi --http :3031 --gevent 1000 --http-websockets --master --wsgi-file app.py --callable app

[johaven]

Related to python-socketio-5.10.0 and python-engineio 4.8.0 but +1 :)

[miguelgrinberg]

Possibly related to #332

[pipozzz]

Hi, I have the same problem, with headers already sent OSError, what is the workaround here pls ?