Fix None value when adding info to auto_map
# What does this PR do?

This should fix the issue encountered in #22983: before testing if `--` in in a value of the auto map, we need to make sure it's not `None`.

Fixes #22983
_The documentation is not available anymore as the PR was closed or merged._<|||||>There are some, it's juss the case when there is only a fast tokenizer that is custom that is not tested.