Just make "length = len(list(s))" if you need to know it.

Any whitespace at the end of the line should also be stripped out.

It's because of that.

If the array of arrays is null/nil or empty

null is not the same as an empty array. You can't read the length of null and that's what the error is about.

You have a typo in your code:

if(lengthArray.lenth){
      return 0
  }

It's length, not lenth. But fixing that would break your code.