A hint as to why it crashes is [here](https://github.com/brain-lang/brainfuck/blob/master/brainfuck.md#increment-).
You're using an `int`, when you should be using a `uint8` for your `dataPointer` variable. Also, [this python example](https://github.com/pocmo/Python-Brainfuck/blob/master/brainfuck.py) can help you precompute a jump table so you don't have to iterate over every instruction every time. If you are still stuck and want the answer (plus some helpful comments), [here is a working example from your code](https://gist.github.com/jyapayne/ab2a0745382481bcdb86977ca7149e11)
