Avoid misleading errors on ambiguity
Clarification and motivation
Type functions like RequireLongerOrSameLength'
that use TypeError
arguments to type families can lead to confusing errors when those type families fail to reduce. Avoid that by explicit matching and perhaps singletons.
Acceptance criteria
Unrelated custom type errors are not reported just because a type family application is stuck. We probably want to avoid any custom type errors for stuck type families, but if any remain they should be intentional.