Following program prints [1] instead of crashing when compiled with -O -fno-full-laziness. Note that it's neccessary to use the extra definition hiddenError instead of calling error directly. The problem might be related to #5557 (closed), which, however, has already been fixed and optimisation is needed to trigger the current bug.

hiddenError = error "hidden error"

main = do
  print $ seq (head (map (\a -> \b -> hiddenError) (hiddenError::[] Bool))) id [1]

I used GHC 7.3.20111022 for triggering this problem.