When we fail to provision tables, for instance via `db init`, we
would get a very unhelpful error message.

To improve this, we can instead provide a more useful error message,
which takes advantage of the `Name` for each `Repository` type.

However, this has flagged that a number of repositories haven't yet
implemented it, so we need to add it.

This is largely _not_ user-facing, as we should only receive these
errors when we're in development, but it's still worthwhile making the
changes.