The crash is caused by libepoxy GL functions pointing to nullptrs.
libepoxy "Automatically initializes as new GL functions are used.",
so to call a function without a GL context bound, the function must
have been called before with a bound context.
This PR ensures there's a valid GL context bound for the whole
`WM_exit` scope.
(4.5 backport candidate)
Pull Request: https://projects.blender.org/blender/blender/pulls/144572
b2b23e3619