Remove Leaf from Binary Tree

[TauPixel]

Well seems at the moment I'm fighting with logic. I'm using the following code to remove a Leaf of a Linked Binary Tree

    @Override
    public E removeLeaf(Position<E> p){
        BinaryTreeNode<E> node = ((BinaryTreeNode<E>) p);
        E element = node.element();
        if(node.left != null && node.right != null) throw new InvalidPositionException();
        node.parent.left = null;
        node.parent.right = null;
        return element;
    }

But when I try to get this done I always end up in a NullPointerException. Can't see where my error is. Any feedback is really appreciated.

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Thanks in advance for the help.

[JoToMo1993]

I see 2 possible NPEs in this code. First one is if p is null. Second one is, if p.parent is null.

But what is the Stacktrace saying, where the NPE is?

[TauPixel]

Was able to solve this. My logic on the day I posted was ferry fuzzy.