老師請問這個報錯是甚麼原因我寫得和老師一樣啊

来源：9-5 LeetCode：133. 克隆图

weixin_慕雪0272820

2021-06-18

/**
 * // Definition for a Node.
 * function Node(val, neighbors) {
 *    this.val = val === undefined ? 0 : val;
 *    this.neighbors = neighbors === undefined ? [] : neighbors;
 * };
 */

/**
 * @param {Node} node
 * @return {Node}
 */
var cloneGraph = function(node) {
    if(!node) return 

    const visited = new Map()

    const dfs =(n) => {
        //copy每個node
        const nCopy = new Node(n.val)
        visited.set( n, nCopy)
        (n.neighbors || []).forEach(ne=>{
            if(!visited.has(ne)){
            dfs(ne)
            }
            nCopy.neighbors.push(visited.get(ne))
        })
    }

    dfs(node)
    return visited.get(node)

};

图片描述