Ensure PyEval_GetGlobals() doesn't set an exception when returning NULL

GitHub fields:

assignee = 'https://github.com/ncoghlan'
closed_at = None
created_at = <Date 2022-04-03.06:41:46.197>
labels = ['type-feature']
title = "Ensure PyEval_GetGlobals() doesn't set an exception when returning NULL"
updated_at = <Date 2022-04-03.06:48:44.524>
user = 'https://github.com/ncoghlan'

bugs.python.org fields:

activity = <Date 2022-04-03.06:48:44.524>
actor = 'ncoghlan'
assignee = 'ncoghlan'
closed = False
closed_date = None
closer = None
components = []
creation = <Date 2022-04-03.06:41:46.197>
creator = 'ncoghlan'
dependencies = []
files = []
hgrepos = []
issue_num = 47204
keywords = []
message_count = 2.0
messages = ['416611', '416612']
nosy_count = 1.0
nosy_names = ['ncoghlan']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'test needed'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue47204'
versions = []