Panic with RequiredTypeArguments and EmptyCase
## Summary
Combining `RequiredTypeArguments` with `EmptyCase` leads to a panic.
## Steps to reproduce
In GHCi:
```
>>> :set -XRequiredTypeArguments
>>> import Data.Kind
>>> let f :: forall (xs :: Type) -> (); f = \case {}
panic! (the 'impossible' happened)
GHC version 9.10.1:
Util: only
CallStack (from HasCallStack):
panic, called at compiler/GHC/Utils/Misc.hs:486:10 in ghc-9.10.1-803c:GHC.Utils.Misc
Please report this as a GHC bug: https://www.haskell.org/ghc/reportabug
```
## Expected behavior
No panic.
## Environment
* GHC version used: 9.10.1
issue