Confusing error message in empty pattern for Data.Complex

[chshersh]

Module Data.Complex from base-4.9.1.0 package fails to parse. When running from REPL:

ghci> parseFile "Complex.hs"
ParseFailed (SrcLoc "Complex.hs" 230 1) "Parse error in pattern: "

At least there's bug in parser somewhere. But it's bad that error message is not helpful enough :(

Relevant lines where parser fails:

226|instance Applicative Complex where
227|  pure a = a :+ a
228|  f :+ g <*> a :+ b = f a :+ g b
229|
230|instance Monad Complex where
231|  a :+ b >>= f = realPart (f a) :+ imagPart (f b)

When I comment line 228 everything works. So parser error in fact is in line number 228.