2-2-4-linked-list, remove tests accept the broken code

[obaibula]

The next broken code is accepted:

@Override
    public T remove(int index) {
        checkIndex(index, size);

        if (index == 0) {
            return removeHead();
        } else if (index == size - 1) {
            return removeTail();
        } else {
            return removeInBetween(index);
        }
    }

    private T removeInBetween(int index) {
        Node<T> previous = getNodeByIndex(index - 1);
        T removed = previous.next.element;
        previous.next = previous.next.next;

        size--;

        return removed;
    }

    private T removeTail() {
        T removed = tail.element;

        Node<T> preTail = getNodeByIndex(size - 2);
        preTail.next = null;
        tail = preTail;

        size--;
        return removed;
    }

    private T removeHead() {
        T removed = head.element;
        head = head.next;
        size--;
        return removed;
    }

Please consider the following example:

LinkedList<Integer> list = LinkedList.of(10);

        System.out.println(list.remove(0));

        System.out.println(list.size());
        System.out.println(list.getLast());

In this example, we can still get the "last" element even if size == 0.

It's necessary to reassign tail, as shown below:

private T removeHead() {
        T removed = head.element;
        head = head.next;
        size--;

        if(head == null){
            tail = null;
        }

        return removed;
    }