This suggestion reflects an improvement to the user popup, the user mention popup, and on the profile page of a user.
Suggestion: Track what page someone is viewing or display "last seen online" text if the user is viewing something they can't access, much like how Xenforo and Invision Community forum providers handle their user profiles.
I'll leave the debug trace for the experts to figure out. No parts of the given debug code have been modified and remain completely untouched from the first installation of Namelessmc v2, in other words, the User.php file has never been modified since I installed Namelessmc v2.
Debug Trace: https://debug.namelessmc.com/QMd3ViSV5T
In short, deleting a user that is currently active (logged in and validated through email) results in a TypeError and crashes the site for a good 4 minutes with the bug before it resolves itself, probably finally processed deleting the user completely and revisiting the broken code and proceeds as normal.
Typed property User::$_main_group must be an instance of Group, null used