Python crash the engine at exit.

A UDN reported various crashes at exit in the embedded Python library. I was able to repro the issue in Release-5.1 and trace it back at the point where python runs its garbage collection in Py_Finalize(). The bug is also random, sometimes it crashed, sometimes it didn't. I used a small init_unreal.py  for QAGame (E:\UE_5.1\QAGame\Content\Python\init_unreal.py) that I attached with this bug.

[Link Removed]

Because the bug is random, I suspect a memory stomp or a race condition. It seems to happen when we alias unreal object in class members. 

Solutions:

• Run the engine with a memory stomp detector
• Build Python 3.9.7 locally and link the library to the Editor to debug Python library itself
• Update to a newer Python version to check if this was a bug fixed in Python.

 Crash group: [Link Removed]

• Copy the init_unreal.py file attached in QAGame Python content folder (QAGame\Content\Python)
• Launch QAGame in the Editor and wait for it to load.
• Close the Editor, notice the crash at exit.