我無法讓它工作。這是我的主文件：const fs = require('fs');  bot.commands = new Discord.Collection();  const commandFiles = fs.readdirSync('./commands/').filter(file => file.endsWith('.js'));  for(const file of commandFiles) {    const command = require(./commands/${file});    bot.commands.set(command.name, command);  } if (message.content == 'ping' || message.content == 'Ping') {   //message.channel.send('Pong');   bot.commands.get('ping').execute(message);和我的文件平.js：module.exports = {  name: 'test',  description: "Tester ting",  execute(message, args) {    message.channel.send("STOR TEST")  }}我收到此錯誤：UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'execute' of undefined我試圖讓我的機器人來拯救我：-）