So what were the errors? All I caught was the index thing at the end, but I would think it would be more about going out of bounds since the topic is iterating

So what were the errors? All I caught was the index thing at the end, but I would think it would be more about going out of bounds since the topic is iterating over objects and arrays. I also thought that looping over object keys using for in, although it does work you should also be checking to see if it object has it as its own property that you declared, or is that overkill in checking keys?