无法阅读财产＆＃34;调度员＆＃34;未定义的

Question

创建音乐模块时，我在制作Discord机器人时遇到了一些问题。它使用ytdl-core和ffmpeg 这是有问题的一行：

if server.dispatcher server.dispatcher.end();

我收到以下错误：

  

无法阅读财产＆＃34;调度员＆＃34;未定义的。

有人能帮助我吗？

// Constants, variables and functions
const ffmpeg = require('ffmpeg')
const Discord = require('discord.js');
const client = new Discord.Client();
const YTDL = require('ytdl-core');
const clientprefix = "//";
const opusscript = require('opusscript');
const moderatorprefix = "> ";
// Functions and variables
var errorEmbedCreate = function(des) {
  return({embed: {color: 16711680, title: ":x: Error",description: des}});
}

var warningEmbedCreate = function(des) {
  return({embed: {color: 16763904, title: ":warning: Warning",description: des}});
}

var embedCreate = function(col,des,tit) {
  return({embed: {color: col, title: tit,description: des}});
}

var cat = "http://random.cat/meow.php"

var servers = [];

function play(connection, message) {
  var server = servers[message.guild.id];

  server.dispatcher = connection.playStream(YTDL(server.queue[0],       {filter:"audioonly"}));

  server.queue.shift();

  server.dispatcher.on("end", function() {
    if (server.queue[0]) play(connection, message);
    else connection.disconnect();
  });
}

每次执行命令时都会创建：

var server = servers[message.guild.id];