Creation and Deletion of users on the User Management page throws errors

[anathemamask]

From @Phi#4271

ALL MODULES DISABLED? True
OS, Hosting, Browser (if applicable): Windows 11, local instance
Short Description of bug: Able to delete last GM user. Error when deleting GM user. Unable to delete player users. Unable to Save and Return after deleting last GM user.
Simple steps to reproduce the bug:

• Open User Management.
• Attempt to delete GM user.
• Attempt to Create new users.
• Attempt to delete player users.
• Attempt to Save and Return.

Screenshots and/or console errors: