Display "uncaught exception" page as content-type text/html When there is an uncaught exception, Drupal 8 displays a simple dump of the exception.

I find that the page is served as 'Content-Type' = 'text/plain', yet it contains HTML:


It looks better to me when I change the code to serve as 'text/html':


I already found the code to change - it's in FinalExceptionSubscriber.php, which outputs


&lt;/br&gt;&lt;/br&gt;
SafeMarkup::format(...) which is documented as



  Formats a string for HTML display by replacing variable placeholders.


My question is:


Does anyone know a reason why the error page is text/plain given that it contains HTML.
Shall I raise an issue and patch?
Thanks @4k4, so it seems that this is a minor bug, but the obvious fix would revert the "Standardize handling" issue.

I have raised this issue and linked it to the other issue.  I don't really understand the code here and would welcome any help to improve the issue text.