JSon instances for Map/Set require Ord constraint

[bladyjoker]

lambda-buffers/runtimes/haskell/lbr-prelude/src/LambdaBuffers/Runtime/Prelude/Json.hs

Line 140 in f5acbc0

instance (Json k, Json v, Ord k) => Json (Map k v) where

sum X = Y | Z
derive Json X

record Test  = {
  test : Map X Integer
}
derive Json Test

The generated code will break because X doesn't have Ord.

See #224