Set Content-Type: text/html in PrettyPageHandler
Set Content-Type: text/html in PrettyPageHandler

This will make the pretty HTML pages work properly even if the user already spat out a different Content-Type header prior to their error.
michabbb-backup/whoops,filp/whoops,michabbb-backup/whoops,staabm/whoops,Vmak11/whoops,Vmak11/whoops,filp/whoops,staabm/whoops