Core Lint error

This produces a long Core lint error:

{-# Language DerivingStrategies #-}
{-# Language GADTs #-}
{-# Language GeneralizedNewtypeDeriving #-}
{-# Language InstanceSigs #-}
{-# Language KindSignatures #-}
{-# Language TypeFamilies #-}
{-# Language TypeInType #-}
{-# Language TypeOperators #-}

import Data.Kind

data DEFUNC :: Type -> Type -> Type where
  (:~>) :: a -> b -> DEFUNC a b

type a ~> b = DEFUNC a b -> Type
    
data LamCons a :: Type ~> Type where
  LamCons :: a -> LamCons a ([a] :~> [a])

class Mk (app :: Type ~> Type) where
  type Arg app :: Type

  mk :: Arg app -> app (a :~> b)

instance Mk (LamCons a :: Type ~> Type) where
  type Arg (LamCons a) = a

  mk :: a -> LamCons (a :~> b)
  mk = LamCons

with ghci -ignore-dot-ghci -fdefer-type-errors -dcore-lint bug.hs on GHC 8.2.1 and 8.3.20171208.