'pydoc -k' fails when some module's loader is not found

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2022-01-12.08:53:18.397>
labels = ['type-bug', 'library', '3.9']
title = "'pydoc -k' fails when some module's loader is not found"
updated_at = <Date 2022-01-12.13:04:25.878>
user = 'https://github.com/dlax'

bugs.python.org fields:

activity = <Date 2022-01-12.13:04:25.878>
actor = 'dlax'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2022-01-12.08:53:18.397>
creator = 'dlax'
dependencies = []
files = []
hgrepos = []
issue_num = 46353
keywords = ['patch']
message_count = 2.0
messages = ['410388', '410389']
nosy_count = 2.0
nosy_names = ['christian.heimes', 'dlax']
pr_nums = ['30557']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue46353'
versions = ['Python 3.9']