Strange TypeError behaviour

TypeError.hs

{-# LANGUAGE TypeInType, TypeFamilies, UndecidableInstances #-}
{-# LANGUAGE UndecidableInstances #-}

import Data.Kind
import GHC.TypeLits (TypeError, ErrorMessage(..))

type family Resolve (t :: Type -> Type) :: Type -> Type where
  Resolve _ = TypeError (Text "ERROR")

-- testOK :: Resolve [] Int
-- testOK = []
--
--  • ERROR
--  • In the expression: []
--    In an equation for ‘testOK’: testOK = []
--

-- testNOTOK1 :: Resolve [] Int
-- testNOTOK1 = ()
--
--  • Couldn't match type ‘()’ with ‘(TypeError ...)’
--    Expected type: Resolve [] Int
--      Actual type: ()
--  • In the expression: ()
--    In an equation for ‘testNOTOK1’: testNOTOK1 = ()
--

-- testNOTOK2 :: Resolve [] Int
-- testNOTOK2 = 1
-- 
--  • No instance for (Num (TypeError ...))
--      arising from the literal ‘1’
--  • In the expression: 1
--    In an equation for ‘testNOTOK2’: testNOTOK2 = 1
--