Visual error when logging out in Firefox

[mxsph]

Describe the bug
If you leave the digital classroom in Firfox and there is a logoutURL set the error page is shown for a short time.

To Reproduce
Steps to reproduce the behavior:

1. Create a classroom with logoutURL
2. Join te classroom in Firfox
3. Leave the classroom

Expected behavior
When leaving the digital classroom, no error message should be displayed (as is the case in Chrome, for example).

Screenshots

Desktop (please complete the following information):

• OS: ManjaroLinux 21.1.3
• Browser: Firefox 93.0 (64-Bit)