8.10.1-alpha2: Unhelpful error message for type signature without corresponding definition

If you compile the following code with GHC 8.10.1-alpha2:

module Bug where

(<+>) :: Int
data (<+>)

You'll get this error message:

$ /opt/ghc/8.10.1/bin/ghc Bug.hs
[1 of 1] Compiling Bug              ( Bug.hs, Bug.o )

Bug.hs:4:1: error:
    The type signature for ‘<+>’ lacks an accompanying binding
      Perhaps you meant ‘<+>’ (Defined at Bug.hs:5:1)
  |
4 | (<+>) :: Int
  | ^^^^^

This error message is profoundly unhelpful, since it complains about missing a binding for <+> but then recommends trying to instead use the name <+>, which is exactly the name I'm using! Note that this does not happen with earlier GHC versions, making this a regression (likely introduced in !760 (merged)):

$ /opt/ghc/8.8.1/bin/ghc Bug.hs
[1 of 1] Compiling Bug              ( Bug.hs, Bug.o )

Bug.hs:4:1: error:
    The type signature for ‘<+>’ lacks an accompanying binding
  |
4 | (<+>) :: Int
  | ^^^^^

Another way to trigger this problem is to use StandaloneKindSignatures:

{-# LANGUAGE StandaloneKindSignatures #-}
module Bug where

type MkT :: T
data T = MkT

$ /opt/ghc/8.10.1/bin/ghc Bug.hs
[1 of 1] Compiling Bug              ( Bug.hs, Bug.o )

Bug.hs:4:6: error:
    The standalone kind signature for ‘MkT’
      lacks an accompanying binding
      Perhaps you meant ‘MkT’ (Defined at Bug.hs:5:10)
  |
4 | type MkT :: T
  |      ^^^

Patch incoming.