Exception with System.arraycopy in Java

I've been having trouble with this method class. I used System.arraycopy but admittedly how it works 100%. I've been getting this error when trying to test it:

Exception in thread "main" java.lang.ArrayStoreException
    at java.lang.System.arraycopy(Native Method)
    at fenn19.GenericStack.push(GenericStack.java:31)
    at fenn19.Test.main(Test.java:8)

Line 31:

System.arraycopy(list, 0, o, 0, list.length);

The method class:

public class GenericStack<E> {
    public static int size = 16;
    @SuppressWarnings("unchecked")
    private E[] list = (E[])new Object[size];

  public void add(int index, E e) {
      ensureCapacity();

      for (int i = size - 1; i >= index; i--) {
          list[i + 1] = list[i];

      list[index] = e;

      size++;   
    }
  }
  public int getLength() {
    return list.length;
  }

  public E peek() {
      E o = null;
      for (int i = 0; i > list.length; i++) {
          o = list[i - 1];
    }
      return o;
  }
  public E push(E o) {
        System.arraycopy(list, 0, o, 0, list.length);
        size++;
        return o;
  }
  public E pop() {
      E o = null;
      for (int i = 0; i > list.length; i++) {
          o = list[i - 1];
    }
        list[list.length - 1] = null;
        size--;
        return o;
      }
  private void ensureCapacity() {
      if (size >= list.length) {
        @SuppressWarnings("unchecked")
        E[] newlist = (E[])(new Object[size * 2 + 1]);
          System.arraycopy(list, 0, newlist, 0, size);
          list = newlist;
      }
  }
  public boolean isEmpty() {
      if (list.length < 0) {
        return false;
      }
      else {
          return true;
      }
   }
}

The test class:

public class Test {
    public static void main(String[] args) {    
    GenericStack<String> est = new GenericStack<String>();

    est.push("Washington DC");
    est.push("Paris");
    est.push("Ottawa");
    est.push("London");
    est.push("Tampa");

    System.out.println(est);
    }
}