jack - 在子程序中插入：预期（Jack 编程语言中的错误

Question

我收到错误

在 BinarySearchTree.jack（第 20 行）中：在子例程中插入：预期（
在 BinarySearchTree.jack（第 25 行）中：在子例程中插入：预期（我有 2 个类，节点：

class Node { 
    field int key; 
        field Node left, right; 
   
    constructor Node new(int data){
        let key = data; 
        let left = null;
        let right = null;
        return this;
    }
    method int getKey() { return key; }
    method Node getLeft() { return left; }
    method Node getRight() { return right; }
    method void setKey(int _key) {let key=_key; return;}
    method void setLeft(Node _left) {let left=_left; return;}
    method void setRight(Node _right) {let right=_right; return;}
}

和 BinarySearchTree：

class BinarySearchTree {
    field Node root;

    constructor BinarySearchTree new() {
        let root = null;
        return this;
    }

    method void insertBST(int num) {
        let root = BinarySearchTree.insert(num,root);
        return;
    }
    method Node insert(int num,Node p) {
        var Node tempNode;
        if (p = null){
            let p = Node.new(num);
            return p;
        }
        if (num < p.getKey()){
            let tempNode = BinarySearchTree.insert(num,p.left);
            do p.setLeft(tempNode);
            return p;
        }
        if (num > p.getKey()){
            let tempNode= BinarySearchTree.insert(num,p.right);
            do p.setRight(tempNode);
            return p;
        }
        do Output.printString("Item in tree and not inserted.");
        return p;
    }
}

我该如何解决这个错误？