This strlen call triggering an exception if an user tried to call the patch command without an authentication token
Indeed, strlen() was used in Phabricator to check if a generic value is a non-empty string.
This behavior is deprecated since PHP 8.1, we use phutil_nonempty_string() as a replacement.

Fix T15599

Remove your arcanist authentication token file (if you have one) and try to call the patch command in a repository.
You should get an error message suggesting you to call the install-certificate command instead of an exception.