Re: Just use Python. You need nothing else.
Yes, really. I didn't just make that up. The problem almost always comes in the form of tabs vs spaces, and is VERY hard to spot. I could be mistaken, of course -- but even if I am, whitespace issues have cost me at least as much time as programming errors.
It would be helpful if the Python interpreter could call out that specific sort of error, but it can't (or at least, the ones that I use don't), so it just ends up being a mysterious failure.