Many security scanners ship invalid mime types, this ensures we return
a very cheap response to the clients and do not log anything.
Previous attempt still re-dispatched the request to get proper error page
but in this specific case we want no error page.
Previously our custom exception handler was unable to handle situations
where an invalid mime type was sent, resulting in a warning log
This ensures we pretend a request is HTML for the purpose of rendering
the error page if an invalid mime type from a scanner is shipped to the app
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
Sam Saffron