It’s a bit like using directories/folders to organise your work - you don’t have to have separate projects in separate folders but it really helps the more projects you have going on. Also once you have two Python projects that require different versions of the same dependency things will get messy.

Are you using a virtual env to isolate the environment of the game from the rest ofyour system? There are a few ways/tools to do it but maybe start here:

https://docs.python.org/3/library/venv.html

If you have the time try the troubleshoot mode to help figure it out - add ons are often the cause

https://support.mozilla.org/en-US/kb/troubleshoot-firefox-crashes-closing-or-quitting

Maybe this method could one day be used with open street map