gh-115539: Allow enum.Flag to have None members

[Jason-Y-Z]

This PR addresses the issue mentioned in Issue #115539 , where having a None member in enum.Flag causes an Exception.
The approach taken is simply to add a isinstance(_, int) check before using the member's value, at 2 relevant places.
This is a small addition so probably can skip-news.

• Issue: enum.Flag with a flag set to None raises an exception #115539

[ethanfurman]

Looks good so far, but we need to also handle cases where the None flag is combined with other flags. Currently it looks like:

>>> Huh.A | Huh.Z                           # A = 1, Z = None
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
    Huh.A | Huh.Z
    ~~~~~~^~~~~~~
  File "/source/python/cpython/Lib/enum.py", line 1571, in __or__
    return self.__class__(value | other)
                          ~~~~~~^~~~~~~
TypeError: unsupported operand type(s) for |: 'int' and 'NoneType'

I think a TypeError is fine, but it needs a better error message.

[bedevere-app]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

[Jason-Y-Z]

I have made the requested changes; please review again

[Jason-Y-Z]

@ethanfurman Thanks for the quick review! Shall I add a News entry or shall we skip news?

[ethanfurman]

We'll skip news and backport.

[miss-islington-app]

Thanks @Jason-Y-Z for the PR, and @ethanfurman for merging it 🌮🎉.. I'm working now to backport this PR to: 3.11, 3.12.
🐍🍒⛏🤖

[bedevere-app]

GH-115694 is a backport of this pull request to the 3.12 branch.

[bedevere-app]

GH-115695 is a backport of this pull request to the 3.11 branch.