Steps to reproduce the issue

Generate an error in admin in Joomla 4

How I did it was to send a private message to another super admin, and then click url below when still being signed in as the sending admin

http://127.0.0.1/administrator/index.php?option=com_messages&view=message&message_id=1

Expected result

403 Forbidden instead of 500 code message
Left menu to be exactly the same as normal

Actual result

Missing toggle navigation
Additional Joomla color logo appeared