A common thing that can be forgotten about / confusing to new people is
that:
1. if you add an object to the `allowed_objs` list but it's also in the
`banned_objs` list -- the ban still takes precedence with no failure
2. if you add an object to the `allowed_objs` list but have not allowed
the DGO in `inputs.jsonc` it will also silently log a failure and
continue.
This PR turns both situations into an explicit error with advice/a
reminder on what to do to fix it.
