In List::set_items, set the last item to null instead of resetting it
In List::set_items, set the last item to null instead of resetting it

I don't know why in the world I called reset_attribute(). The docs don't
mention calling it in this case. Calling reset_attribute() on an index
(after map) doesn't remove all items after the index like
List::set_items should. Setting the index to null does remove them like
the docs state.

jminer/clear-coat