Out of scope error with -fprefer-byte-code and breakpoints

Ticket related to #22955, extracted from Mercury's codebase.

Given two files:

A.hs

module A where

import B

foo :: Bool
foo = True

B.hs

module B where

class Eq a => C a where
  get :: a

instance C Int where
  get = let x = x in x
  {-# INLINE get #-}

perform the following:

1. Remove *.hi *.o files.
2. Run ghci -fprefer-byte-code -fbyte-code-and-object-code -dlint A and quit.
3. Run ghci -fprefer-byte-code -fbyte-code-and-object-code -dlint A again and evaluate foo.

In 9.6, this fails STG Lint:

$ ghc --interactive -fprefer-byte-code -fbyte-code-and-object-code -dlint A 
GHCi, version 9.6.2: https://www.haskell.org/ghc/  :? for help
Ok, two modules loaded.
ghci> foo
*** Stg Lint ErrMsgs: in Pre-unarise ***
<no location info>: warning:
     [RHS of $fCInt :: C Int]
    $fCInt1_iNi :: Int is out of scope
*** Offending Program ***
$fCInt :: C Int
[GblId[DFunId]] =
    C:C! [$fEqInt $fCInt1_iNi];

...

If -dlint is not used, then 9.6 fails with a panic in nameModule.

In master, this fails Core Lint:

ghci> foo
*** Core Lint errors : in result of CorePrep ***
<no location info>: warning:
    Out of scope: x_iO7 :: forall {t}. t
                  [LclId]

If -dlint is not used, then master evaluates foo correctly.

The error disappears with -fno-break-points. The change in behavior between 9.6 and master happened in c59fbb0b. Looks like it improved matters but problems remain.