Bug report

This code is problematic:

Why? Py_GenericAlias can return NULL in different cases:

So, we need to check for NULL.

Linked PRs

• gh-121660: Fix ga_getitem by explicitly checking for NULL result #121661
• [3.13] gh-121660: Fix ga_getitem by explicitly checking for NULL result (GH-121661) #121761
• [3.12] gh-121660: Fix ga_getitem by explicitly checking for NULL result (GH-121661) #121762