notify handler's updateItems function shifts the order of select items

During delete of a select item, the function moves the item at the end of the array to the deleted item's position. So if the following operations are done within the same update cycle, an already-exists-error will happen, because after deleting A, add(B) will come in front of delete(B).

delete(A), delete(B), add(A), add(B)

To fix it, all deletes should be done before adds.