"Could not load photos folder" when userid is numeric

[SystemKeeper]

Describe the bug
When the userid is numeric (e.g. "1234") the following error is shown on the dashboard:

This has been fixed in stable30 (IIRC it was the dependency bumps in #2641). The issue still exists in stable31 and in master.
Adding it here for reference.

[tohaase]

Same error notification, different logs. Fresh install with 30.0.5, update to 30.0.6, update to 31.0.0 - the notification still occurs on public shared links. 😥