GHC panic with invalid expression

Hi, I recently discovered this expression causes GHC to panic. Shouldn't it handle this more gracefully? Perhaps saying something like "That expression is not valid. <Further Explanation>"

Invalid expression:

g :: (a->b) a

Prelude> g :: (a->b) a
ghc: panic! (the 'impossible' happened)
  (GHC version 8.2.1 for x86_64-apple-darwin):
	repSplitAppTys
  a_a1Lz[sk:1]
  b_a1LA[sk:1]
  []
  Call stack:
      CallStack (from HasCallStack):
        prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1133:58 in ghc:Outputable
        callStackDoc, called at compiler/utils/Outputable.hs:1137:37 in ghc:Outputable
        pprPanic, called at compiler/types/Type.hs:808:9 in ghc:Type

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

Trac metadata

Trac field	Value
Version	8.2.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system	MacOS X
Architecture

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information

Admin message

GHC panic with invalid expression