Mentioned in [53187] on Core SVN:
Users: Avoid warning on `the_modified_author` when `get_userdata()` returns `false`.

Created ticket #55420 on Core Trac:
Warning thrown by method get_the_modified_author if author was removed

Mentioned in [47815] on Core SVN:
Site Health: Use `WP_Theme::parent()` in the inactive themes test as a more reliable check that the parent theme exists.

Created ticket #49934 on Core Trac:
PHP Notice: Trying to get property 'name' of non-object in ...