Out of range TagList access should return null instead of throwing errors

[LOOHP]

This PR adds a range check before accessing tag lists. In the documentation, methods are clearly stated that the target object "or null if none is stored at the provided location". Therefore if an item at index in a tag list does not exist, null should be returned instead of an out of bound exception.

Side note: Are variables named "notCompound" throughout different methods typos of "nbtCompound", or is it intentional?

[BananaPuncher714]

The notCompound variables aren't typos, rather bad naming when I was writing it in the first place. It was more or less because it wasn't the compound for something, and I think copy and paste made it lose its meaning in other places.

[LOOHP]

Got it, thanks for the info!