ICSHWI-9030: Refine error page

In order to make the error handler (that users should probably never see!) more user-friendly, we hide the stack trace by default. Furthermore, we add a notification that the users should come to us if they see an error with some regularity.

requested review from @johnsparger, @imretoth, @zoltanrunyo, @krisztianloki, and @anderslindh1

assigned to @simonrose

changed target branch from master to develop

approved this merge request

added 11 commits

• f45b21b3...97c2dc79 - 10 commits from branch develop
• 87623536 - Add 'show details' button to hide stack

Compare with previous version

enabled an automatic merge when the pipeline for 87623536 succeeds

mentioned in commit 0fc2df0d

merged