[ Bug] Some occasional exception - apparently handled, but then the webpage stops working

Type of Issues (Enhancement, Error, Bug, Question)

Bug

Operating System

Linux

Python version

3.7.8

PySimpleGUI Port and Version

<module 'PySimpleGUIWeb' from '/home/pi/.local/lib/python3.7/site-packages/PySimpleGUIWeb/__init__.py'>

>>> print(sg.version)     # PySimpleGUI version number
0.39.0  Released 6-Jun-2020

>>> print(sg.tclversion_detailed)   # tkinter detailed version number (in PySimpleGUI version 4.29.0+)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: module 'PySimpleGUIWeb' has no attribute 'tclversion_detailed'

>>> print(sg.sys.version) # Python version number
3.7.3 (default, Jul 25 2020, 13:03:44) 
[GCC 8.3.0]

Your Experience Levels In Months or Years

2_________ Python programming experience

30_________ Programming experience overall
no_________ Have used another Python GUI Framework (tkinter, Qt, etc) previously (yes/no is fine)?

You have completed these steps:

• Read instructions on how to file an Issue
• Searched through main docs http://www.PySimpleGUI.org for your problem
• Searched through the readme for your specific port if not PySimpleGUI (Qt, WX, Remi)
• Looked for Demo Programs that are similar to your goal http://www.PySimpleGUI.com
• Note that there are also Demo Programs under each port on GitHub
• Run your program outside of your debugger (from a command line)
• Searched through Issues (open and closed) to see if already reported
• Try again by upgrading your PySimpleGUI.py file to use the current one on GitHub. Your problem may have already been fixed but is not yet on PyPI.

Description of Problem / Question / Details

after some time, processing some button clicks (as simple as if pressed, increase an integer.)
this can spawn on the console as web page stops working:

----------------------------------------
Exception happened during processing of request from ('192.168.1.41', 58336)
Traceback (most recent call last):
  File "/usr/lib/python3.7/socketserver.py", line 650, in process_request_thread
    self.finish_request(request, client_address)
  File "/usr/lib/python3.7/socketserver.py", line 360, in finish_request
    self.RequestHandlerClass(request, client_address, self)
  File "/home/pi/.local/lib/python3.7/site-packages/PySimpleGUIWeb/PySimpleGUIWeb.py", line 3360, in __init__
    super(Window.MyApp, self).__init__(*args,  static_file_path={'C':'c:','c':'c:','D':'d:', 'd':'d:', 'E':'e:', 'e':'e:', 'dot':'.', '.':'.'})
  File "/home/pi/.local/lib/python3.7/site-packages/remi/server.py", line 313, in __init__
    super(App, self).__init__(request, client_address, server)
  File "/usr/lib/python3.7/socketserver.py", line 720, in __init__
    self.handle()
  File "/usr/lib/python3.7/http/server.py", line 426, in handle
    self.handle_one_request()
  File "/usr/lib/python3.7/http/server.py", line 414, in handle_one_request
    method()
  File "/home/pi/.local/lib/python3.7/site-packages/remi/server.py", line 566, in do_GET
    ws = WebSocketsHandler(self.headers, self.request, self.client_address, self.server)
  File "/home/pi/.local/lib/python3.7/site-packages/remi/server.py", line 129, in __init__
    socketserver.StreamRequestHandler.__init__(self, *args, **kwargs)
  File "/usr/lib/python3.7/socketserver.py", line 720, in __init__
    self.handle()
  File "/home/pi/.local/lib/python3.7/site-packages/remi/server.py", line 145, in handle
    clients[self.session].websockets.remove(self)
ValueError: list.remove(x): x not in list
----------------------------------------
Saved:  Normal
Saved:  Normal
----------------------------------------
Exception happened during processing of request from ('192.168.1.41', 58454)
Traceback (most recent call last):
  File "/usr/lib/python3.7/socketserver.py", line 650, in process_request_thread
    self.finish_request(request, client_address)
  File "/usr/lib/python3.7/socketserver.py", line 360, in finish_request
    self.RequestHandlerClass(request, client_address, self)
  File "/home/pi/.local/lib/python3.7/site-packages/PySimpleGUIWeb/PySimpleGUIWeb.py", line 3360, in __init__
    super(Window.MyApp, self).__init__(*args,  static_file_path={'C':'c:','c':'c:','D':'d:', 'd':'d:', 'E':'e:', 'e':'e:', 'dot':'.', '.':'.'})
  File "/home/pi/.local/lib/python3.7/site-packages/remi/server.py", line 313, in __init__
    super(App, self).__init__(request, client_address, server)
  File "/usr/lib/python3.7/socketserver.py", line 720, in __init__
    self.handle()
  File "/usr/lib/python3.7/http/server.py", line 426, in handle
    self.handle_one_request()
  File "/usr/lib/python3.7/http/server.py", line 394, in handle_one_request
    self.raw_requestline = self.rfile.readline(65537)
  File "/usr/lib/python3.7/socket.py", line 589, in readinto
    return self._sock.recv_into(b)
ConnectionResetError: [Errno 104] Connection reset by peer
----------------------------------------

Code To Duplicate

I cannot think of how to narrow it down, as I do not see any meaningful order of operatoin that causes this.

Start with PySimpleGUIWeb.py around line 3360 and the corresponding request handling in remi/server.py, especially websocket cleanup around line 145 and do_GET around line 566. Reproduce the intermittent list.remove and connection-reset failures if possible, then define a regression test that confirms the web page remains usable after the request error.