Error Handling

While neither Quokka nor any of it's sub crates make displaying errors very easy (for now) the recommanded way so far is to create a middleware which checks for a Extension<Error> on the created response and act according to it. This middleware might only be attached to your router, returned by the get_router method as you will unlikely handle someone else's errors. And in the case someone else uses your errors you can make your error handling middleware public.