panic! failed to detect OverLit; OverloadedStrings and -fdefer-type-errors
Here is an example program:
```haskell
{-# LANGUAGE OverloadedStrings #-}
import Data.Text
foo :: [Text] -> Bool
foo "HI" = True
foo _ = False
main = pure ()
```
This causes GHC (and ghci) to crash, when run like this:
ghc -fdefer-type-errors Test1.hs
```
[1 of 2] Compiling Main ( Test1.hs, Test1.o )
<no location info>: error:
panic! (the 'impossible' happened)
GHC version 9.12.2:
failed to detect OverLit
"HI"
Call stack:
CallStack (from HasCallStack):
callStackDoc, called at compiler/GHC/Utils/Panic.hs:190:37 in ghc-9.12.2-inplace:GHC.Utils.Panic
pprPanic, called at compiler/GHC/HsToCore/Pmc/Desugar.hs:221:22 in ghc-9.12.2-inplace:GHC.HsToCore.Pmc.Desugar
Please report this as a GHC bug: https://www.haskell.org/ghc/reportabug
```
I've confirmed that the bug occurs in these GHC versions:
- GHC git master branch from a few weeks ago (version reported as 9.15.20260111)
- GHC 9.12.2
GHC 9.10.2, GHC 9.8.2, and GHC 9.4.8 all give the expected outout:
```
Test1.hs:6:5: warning: [GHC-18872] [-Wdeferred-type-errors]
• Couldn't match type ‘Text’ with ‘Char’
arising from the literal ‘"HI"’
• In the pattern: "HI"
In an equation for ‘foo’: foo "HI" = True
|
6 | foo "HI" = True
| ^^^^
```
issue