#26 Constraint violations in relations are reported strangely.

[baz bishop]

When a type constraint violation is detected, a named user constraint violation is reported with an anonymous ID.

This is confusing. There should be a special constraint type for relations, similar to attribute constraint violations.

The violation can be caused by:

relation R( ofType A )

instance b memberOf B

relationInstance bad R(b) // ** b is not a memberOf A