#16 Ошибки в реализации стека

Расскажите про все проблемы в коде:

public class Stack {
    private Object[] elements;
    private int size = 0;
    private static final int DEFAULT_INITIAL_CAPACITY = 16;

    public Stack() {
        elements = new Object[DEFAULT_INITIAL_CAPACITY];
    }

    public void push(Object e) {
        ensureCapacity();
        elements[size++] = e;
    }

    public Object pop() {
        if (size == 0)
            throw new EmptyStackException();
        size-=1;
        Object some = elements[size];
        elemens[size] = null;
        return some;
    }

    /** Ensure space for at least one more element, roughly doubling the capacity each time the array needs to grow.*/
    private void ensureCapacity() {
        if (elements.length == size)
            elements = Arrays.copyOf(elements, 2 * size + 1);
    }
}