Looking for solution in unexpected results from BST implementation

I have this piece of code down below for removing a node from a BST:

private TreeNode<T> remove(T data, TreeNode<T> current) {
        if(current == null) {
            throw new InputMismatchException("The data element trying to be removed couldn't be found.");
        }
        else if(data.compareTo(current.data) < 0) {
            current.left = remove(data, current.left);
        }
        else if(data.compareTo(current.data) > 0) {
            current.right = remove(data, current.right);
        }
        else {
            if(current.right != null && current.left == null) {
                return null;
            }
            else if(current.right == null && current.left != null) {
                if(current.right != null) {
                    return current.right;
                }
                return current.left;
            }
            else {
                current.right = findSuccessor(current.right, current);
            }
        }

        size--;
        return current;
    }

it keeps on giving odd results and I can’t figure out why. Can someone please help?

>Solution :

In your else statement when asserting current.right, you should be checking if it is null rather than if it isn’t.

if(current.right == null && current.left == null) {
  return null;
}