The main `Server.Internal` module was getting a bit large for my taste.
It now contains just the instances. All the administrative utilities
are in their own dedicated modules.
Due to the delayed treatment of checks during the server interpretation,
we now have the ability to produce "better" error codes for certain
APIs. This change introduces test cases for some of these situations and
their new, desired results. These tests would mostly fail with the old
approach to routing.
