New not-in-scope behaviour + deferred typed holes = disappearing error messages

The following code snippet is well-typed, and GHC is fine with it:

{-# LANGUAGE TypeFamilies #-}

import Control.Monad  -- comment this out to cause error
import Data.IORef

class MonadRef m where
    type Ref m :: * -> *
    newRef :: a -> m (Ref m a)
    readRef :: Ref m a -> m a

instance MonadRef IO where
    type Ref IO = IORef
    newRef = newIORef
    readRef = readIORef

main :: IO ()
main = newRef (pure ()) >>= join . readRef

However, if one removes the import of Control.Monad, then GHC treats join as a typed hole due to #10569 (closed), but fails to infer its type, causing errors:

test.hs:17:8-23: error: …
    • Couldn't match type ‘Ref m0’ with ‘IORef’
      ...
test.hs:17:29-32: error: …
    Variable not in scope: join :: m0 (f0 ()) -> IO ()

By default the not-in-scope error is reported, but if -fdefer-typed-holes is in effect, only the type error is reported and the scope error just vanishes, leaving the user (at least me) puzzled.

Not-in-scope errors should always be reported.