gh-146388: Add null check for sym_new(ctx) in make_bottom

[A0su]

optimizer_symbols.c: make_bottom NULL deref when arena full

sym_new(ctx) at line 1535 can return NULL when the type arena is full. Result immediately dereferenced without check. Every other sym_new call site checks for NULL.

This is a sub-issue of #146102 with gist details

• Issue: optimizer_symbols.c: make_bottom NULL deref when arena full #146388

[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[aisk]

I think this fix is simple enough which doesn't requires a test, but the news entry is required. Can you add it follow the Dev Guide? https://devguide.python.org/getting-started/pull-request-lifecycle/#updating-news-and-what-s-new-in-python

[A0su]

@aisk, blurb added. Thanks for the review!

[Fidget-Spinner]

This doesn't tell much. Can it be more descriptive please? Something like

Handle when JIT optimizer runs out of space when dealing with contradictions.

[vstinner]

LGTM. I'm not sure that the NEWS entry is worth it, it's a corner case which is unlikely to occur in practice, no?