panic when file contains unsupported extension
## Summary
When trying to use a `LANGUAGE` pragma with an extension that doesn't exist, the normal error message appears, but also a GHC panic.
## Steps to reproduce
Compiling
```haskell
{-# LANGUAGE Extension #-}
```
yields
```
ghc: panic! (the 'impossible' happened)
GHC version 9.3.20210529:
non-driver message in preprocess
/mnt/c/Users/user/haskell/foo/extension.hs:1:14: error:
Unsupported extension: Extension
Call stack:
CallStack (from HasCallStack):
callStackDoc, called at compiler/GHC/Utils/Panic.hs:186:37 in ghc:GHC.Utils.Panic
pprPanic, called at compiler/GHC/Driver/Pipeline.hs:164:21 in ghc:GHC.Driver.Pipeline
```
## Expected behavior
Show the same error message, but without panicking
## Environment
* GHC version used: 9.3.20210529
Optional:
* Operating System: Arch on WSL2 on Windows 10
* System Architecture: x86_64
issue