For syntax highlighting on the exception page we still use prettify.js, which like most Google projects has been abandoned. So we should really replace it with something better, like highlight.js.

There was actually an attempt before, but it failed because of interdependencies with mojolicious.org. That is no longer a problem, because assets are not shared anymore.

For testing you can use the included example app examples/responses.pl (perl -Ilib examples/responses.pl daemon). The screenshot above was taken of a request for http://127.0.0.1:3000/res5.