T20363.hs:23:10: error: [GHC-55287]
    • The newtype constructor pattern
      does not have a fixed runtime representation.
      Its kind is:
        TYPE NilRep
      (Use -fprint-explicit-coercions to see the full type.)
    • In the pattern: MkNT (##)
      In an equation for ‘test1b’: test1b (MkNT (##)) = 0