At the current moment, 404 and 500 errors are served from static, non-template pages in /public.
Error pages should appear to be "in-app". Further, they need to be consistent across the application. An important part of this effort is code review to make sure that errors are handled in an efficient and non-circuitous fashion.
I'm outlining some goals here:
Route all exception handling* to ErrorsController
Progress on #897
* Excludes Authorization issues, for now.