`Set` is not a valid Haskell type

[jespercockx]

Discovered during my presentation at AIM XLI:

foo : Set → Int
foo _ = 42
{-# COMPILE AGDA2HS foo #-}

goo : ∀ {a : Set₁} → (a → Int) → Bool
goo _ = True
{-# COMPILE AGDA2HS goo #-}

test = goo foo
{-# COMPILE AGDA2HS test #-}

This produces the following invalid Haskell:

foo :: Int
foo = 42

goo :: (a -> Int) -> Bool
goo _ = True

test :: Bool
test = goo foo

It should reject the definition of test instead, since the type parameter a should only be instantiated with a valid Haskell type.