T20363_show_co.hs:23:10: error: [GHC-55287]
    • The newtype constructor pattern
      does not have a fixed runtime representation.
      Its type is:
        ((# #) |> (TYPE (Sym (T20363_show_co.D:R:NilRep[0])))_N) :: TYPE
                                                                      NilRep
    • In the pattern: MkNT (##)
      In an equation for ‘test1b’: test1b (MkNT (##)) = 0