Add error handler.

[emlynwest]

Make sure messages are translatable, see #25

[sagikazarmark]

By error handler you mean....

Something like Whoops?

[emlynwest]

Yep!

[WanWizard]

Whoops is already present? Or at least it was... ;)

[sagikazarmark]

I think it is, but it received some updates, maybe even a major version since then.

[emlynwest]

I've not gotten around to adding it back in after the re-work. Currently it's not there.

[WanWizard]

Ah, ok.