Fatal PHP error after enabling the module

Thanks for logging this @ecvandenberg. It's been years since I last worked on this module, since my time is always super limited. But good to hear that it would be useful to you.

I've just fixed this issue and made some other minor improvements. Can you try the latest dev version to see if it's fixed and works for you?

And thank you for a quick fix!
It works in a fresh D10 website, but with some remarks.
When you add or remove a node type at /admin/config/system/reference-access it immediately has effect to the user trying to get access. I simulate this by having a private browser window with the dedicated user logged in and trying to access the restricted node.
But when you change the specific nodes the user should have access to, that does not has effect before clearing all cache.

In an older D9.5.10 it works partly. Add or remove a node type at /admin/config/system/reference-access it immediately has effect.
But adding a specific nodes to a user does not have any effect. The access stays forbidden.

I do not see any errors in the CMS log. If you have any hints in how I could debug this better please let me know.
This site used to have other access modules like access by term. But these are all uninstalled now.