Thanks for the help(I finished), turns out my problem was that I was calling functions within a function
so when I returned [] it wasnt passed on but stayed in the local memory of the outer function.

I had some problems understanding the error handling too.

Errors, if:

n is not a number
n not an integer
n is negative or 0

The three functions should respectively return [], [[],[]] and [].
So the first function should return [], the second one should return [[],[]], and the last [].
I hope this is going to help you.