TypeError return value of EntityStorageBase::getEntityClass() must be of the type string

Hey @joseph.olstad
Is this issue still exists as I tried with the below version:
Drupal: 11.1.5
Key: 1.20
smtp: 1.4.0
symfony_mailer: 1.5.0
symfony_mailer_lite: 2.0.2

Below are the screenshot of overriding smtp username with custom test key.

Am I missing something here? could you check with the latest version of modules and update the issue accordingly?

hmm, ok we're still using the patch, my contract with the client using this has only a few hours left so I won't be able to re-test.

As unable to reproduce with latest dev of key and dependencies mentioned in description, will close the issue as it is functioning as designed. Please feel free to open a new issue if the problem persists.

I have a feeling that there is a bug here in how we're returning the class type, but not sure how to reproduce it yet.

Why does the URL have ?ajax-form? That's not part of the normal action link. Is there another contrib at play which AJAX-ifies forms?