9.6 assertion failure - constraint vs type

module Data.NonEmpty.Class where

import qualified Control.DeepSeq as DeepSeq

class NFData f where
   rnf :: DeepSeq.NFData a => f a -> ()

instance NFData Maybe where
   rnf = DeepSeq.rnf

> ~/head.hackage/ghc/bin/ghc Class.hs -O
<no location info>: error:
    panic! (the 'impossible' happened)
  GHC version 9.6.0.20230220:
	ASSERT failed!
  Coercion = Kind (Sym (N:NFData[0] <a_aMw>_N))
  LHS ty = *
  RHS ty = Constraint
  cs = Tc(0)
  coercion role = nominal
  Call stack:
      CallStack (from HasCallStack):
        assertPpr, called at compiler/GHC/Core/Coercion.hs:1126:5 in ghc:GHC.Core.Coercion
        mkSelCo_maybe, called at compiler/GHC/Core/Coercion.hs:1118:16 in ghc:GHC.Core.Coercion
        mkSelCo, called at compiler/GHC/Core/Coercion.hs:620:5 in ghc:GHC.Core.Coercion
        mkRuntimeRepCo, called at compiler/GHC/Core/Unify.hs:1584:16 in ghc:GHC.Core.Unify
  CallStack (from HasCallStack):
    panic, called at compiler/GHC/Utils/Error.hs:454:29 in ghc:GHC.Utils.Error


Please report this as a GHC bug:  https://www.haskell.org/ghc/reportabug