Discord Bot抓取Reddit梗图报Cannot read property 'send' of undefined如何解决

报错根因 #

你的报错核心由两个问题触发：

1. 递归调用execute方法时参数传参错位：方法定义的入参顺序是client, message, cmd, args, Discord，但你递归调用时仅传了message, args, Discord三个参数，导致方法内的message变量被赋值为你传入的args，最终为undefined，调用message.channel.send时直接抛出Cannot read property 'send' of undefined错误
2. 异常捕获范围不完整：你仅把发送Embed的逻辑放在了try catch块中，前置的Reddit资源请求、URL格式校验、递归调用逻辑都在捕获范围外，出错后无法被catch到，就会抛出未处理的拒绝异常

修复点 #

• 修正递归调用的参数顺序，确保和方法定义的入参顺序一致
• 新增URL有效性前置校验，避免URL为undefined时调用endsWith方法报错
• 扩大try catch覆盖范围，将所有异步逻辑都纳入异常捕获
• 新增重试次数上限，避免连续拿到非图片格式的资源时触发无限递归，导致栈溢出
• 优化随机索引生成逻辑，避免生成负数索引

修复后代码 #

const randomPuppy = require('random-puppy');
const snekfetch = require('snekfetch');
const { MessageEmbed } = require('discord.js')

module.exports ={
  name: 'meme',
  description: "generates memes",
  // 新增retryTimes参数，默认重试次数为3
  async execute(client, message, cmd, args, Discord, retryTimes = 3){
    // 所有逻辑放入try catch块
    try {
      let reddit = [
        "meme",
        "AnimeFunny",
        "animememes",
        "dankmemes",
        "dankmeme",
        "wholesomememes",
        "meirl",
        "me_irl",
        "2meirl4meirl",
        "AdviceAnimals"
      ]

      // 优化随机数生成逻辑，直接生成合法索引，无需额外判断负数
      let random = Math.floor(Math.random() * reddit.length);
      let subreddit = reddit[random];

      console.log(`Chose ${subreddit} since random was ${random}`)
      const url = await randomPuppy(subreddit).catch(() => {});
      console.log(`URL is  ${url}`)
      // 先判断url存在，再判断格式；如果重试次数耗尽就抛错
      if (!url || (!url.endsWith('.png') && !url.endsWith('.jpg'))) {
        if(retryTimes <= 0) throw new Error('多次重试未获取到有效图片资源')
        // 修正参数传递，带上所有入参，重试次数减1
        return this.execute(client, message, cmd, args, Discord, retryTimes - 1);
      }
      const res = await snekfetch.get(url).catch(() => {});
      console.log(`RES is  ${res}`)
      if(!res) throw new Error('资源请求失败')

      const memeEmbed = new MessageEmbed()
        .setColor('RANDOM')
        .setTitle(`Meme From /r/${subreddit}`)
        .setImage(`${url}`)
        .setTimestamp()
        .setFooter(`${url}`)

      await message.channel.send({ embeds: [memeEmbed] }).catch(err => {
        console.error(err);
      });
    } catch (err) {
      console.error(err)
      // 发错误消息前用可选链判断对象存在，避免二次报错
      message?.channel?.send(`An error occured whilst attempting to retrieve a meme, Please try again`)
    }
  }
}

内容的提问来源于stack exchange，提问作者NaturalTwitch