fix: Only return missing from accounts when truly missing

• fix: When LDAP + accounts data aren't consistent, we should error

This can be an issue where one of the 2 driving services don't return data as expected. Rather than return data we can't be fully confident in, the service will instead error out.

Resolves #114 (moved)

• fix: Only return missing from accounts when truly missing

Previously, any non-handled error code would fall through and indicate a missing user, which led to a lot of strange errors. This inversion means that we will more consistantly fail safely than return possibly incorrect missing users.

Resolves #113 (moved)