Need a better error message for absence PrimBytes (DataFrame t ds) instance

[achirkin]

When a code requires PrimBytes (DataFrame t ds), GHC uses a
deriving instance PrimBytes (Array t ds) => PrimBytes (DataFrame t ds),
which, in turn, requires PrimBytes (Array t ds).
Array t ds is a type family; only individual members of the type family have the instance.
To make things worse, there are other instances of PrimBytes defined in easytensor-vulkan.
And GHC starts to panic (Overlapping instances for PrimBytes).

Need to try to reconsider a combination of TypeError and OverlappingInstances to improve this.

The issue comes from a comment #4 (comment).

[achirkin]

Since version 2 of easytensor, there is at most one incoherent instance of every class - the one that depends on KnownBackend. That solves the issue.