Levity-polymorphic join point crashes 8.2

This program (derived from D2858) crashes both GHC 8.0 and 8.2

{-# LANGUAGE ViewPatterns, PatternSynonyms #-}

module Foo where

data PrimOp = AddOp | Add2Op | OtherOp | BotherOp

data Expr = Var PrimOp | App Expr Expr | BApp [Expr] | BOp Expr Expr | L Integer

pattern BinOpApp  :: Expr -> PrimOp -> Expr -> Expr
pattern BinOpApp  x op y =  Var op `App` x `App` y

pattern (:+:) :: Expr -> Expr -> Expr
pattern x :+: y <- BinOpApp x (isAddOp -> True) y

isAddOp :: PrimOp -> Bool
isAddOp AddOp  = True
isAddOp Add2Op  = True
isAddOp _      = False

pattern (:++:) :: Integer -> Expr -> Expr
pattern l :++: x <- (isAdd -> Just (l,x))

isAdd :: Expr -> Maybe (Integer,Expr)
{-# INLINE isAdd #-}
isAdd e = case e of
   L l :+: x   -> Just (l,x)
   x   :+: L l -> Just (l,x)
   _           -> Nothing

Reason: the matching function, generated by the pattern synonym :++:, has a levity-polymorphic join point.

1. 0 has a Lint Error. 8.2 crashes with

  (GHC version 8.2.1.20171024 for x86_64-unknown-linux):
	runtimeRepPrimRep
  typePrimRep (r_a1kX :: TYPE rep_a1kW)
  rep_a1kW
  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/simplStg/RepType.hs:360:5 in ghc:RepType
        runtimeRepPrimRep, called at compiler/simplStg/RepType.hs:342:5 in ghc:RepType
        kindPrimRep, called at compiler/simplStg/RepType.hs:305:18 in ghc:RepType
        typePrimRep, called at compiler/simplStg/RepType.hs:128:19 in ghc:RepType

I think this is just #13394 (closed), #14393 (closed) again. It was fixed in #14393 (closed) of that ticket, but the fix has not yet been transferred to 8.2.