ghc: panic! (the 'impossible' happened)

*Main> :print return
ghc: panic! (the 'impossible' happened)
  (GHC version 8.8.4 for x86_64-unknown-linux):
        isUnliftedType
  t1_acZX[rt] :: TYPE t0_acZW[rt]
  Call stack:
      CallStack (from HasCallStack):
        callStackDoc, called at compiler/utils/Outputable.hs:1159:37 in ghc:Outputable
        pprPanic, called at compiler/types/Type.hs:2277:10 in ghc:Type

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

To reproduce:

1. git clone https://github.com/nbloomf/webdriver-w3c.git
2. I edited stack.yaml, changed the resolver to url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/16/28.yaml
3. stack ghci webdriver-w3c:webdriver-w3c-intro
4. :print return in ghci

My environment is "Windows Subsystem for Linux", Debian on Windows 10 using a recently upgraded version of stack.