Er gaat iets fout maar kan de fout niet vinden!

CODE:
------------------------

const discord = require("discord.js");
const botConfig = require("./botconfig.json");

const fs = require(`fs`);


const bot = new discord.Client();
bot.command = new discord.Collection();

fs.readdir("./commands/" , (err, files) => {

    if(err) console.log(err);

    var jsFiles = files.filter(f => f.split(".").pop() === "js");

    if (jsFiles.length <= 0) {
        console.log("Kon geen files vinden!");
        return;
    }

    jsFiles.forEach((f, i) => {

        var fileGet = require(`./commands/${f}`);
        console.log(`De file ${f} is geladen`);

        bot.commands.set(fileGet.help.name, fileGet);

    })


});


bot.on("ready", async () => {

    console.log(`Zuidland Bot is online!`);

    bot.user.setActivity("Zuidland Roleplay", {type: "PLAYING"});
});

bot.on("message", async message => {

    // Als bot bericht stuurt stuur dan terug.
    if (message.author.bot) return;

    if (message.channel.type === "dm") return;

    var prefix = botConfig.prefix;

    var messageArray = message.content.split(" ");

    var command = messageArray [0];

    var arguments = messageArray.slice(1);

    if( command === `${prefix}hallo`){

        return message.channel.send("Hallo!");
    }


});

bot.login(botConfig.token);

----------------------------------------
ERROR:

[nodemon] 1.19.1
[nodemon] to restart at any time, enter `rs`
[nodemon] watching: *.*
[nodemon] starting `node index.js`
De file hallo.js is geladen
C:\Users\kianv\3D Objects\ZuidlandBot\index.js:26
        bot.commands.set(fileGet.help.name, fileGet);
                     ^

TypeError: Cannot read property 'set' of undefined
    at jsFiles.forEach (C:\Users\kianv\3D Objects\ZuidlandBot\index.js:26:22)
    at Array.forEach (<anonymous>)
    at fs.readdir (C:\Users\kianv\3D Objects\ZuidlandBot\index.js:21:13)
    at FSReqCallback.args [as oncomplete] (fs.js:145:20)
[nodemon] app crashed - waiting for file changes before starting...