How to fix object 'property undefined' keyv/discordjs

Question

I am currently making the shop for my bot, and I am doing the buy command. I have decided to store the user's inventory as an object in the database, however, when I first try to buy and item from the shop (in this case, the fan), it makes the (blank) object, but then it returns:

UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'fan' of undefined

Here is the code: https://github.com/boomermath/grapeoverhaul/blob/master/commands/t.js

module.exports = {
    name: 't',
    description: 'dig to earn stars',
    cooldown: 0,
    execute(message, args, d) {
//blank object to initialize in the db
const blankObj = {}
//items in the shop and their cost
const itemCost = {
    fan: 100,
    orangedetector: 100,
    mangodetector: 50,
    carrotdetector: 50,
    starmagnet: 100,
    starmill: 400
}
async function buy() {
     //get person's inventory
    let have = await d.items.get(message.author.id);
    //if they arent in the db, initialize
    if (have === undefined || have === null) {
    await d.items.set(message.author.id, blankObj)
    }
    //argument parsing, get item and number of items user wants
    let regex = /\d+/g;
    let numberOfItemsRaw = args.join(' ').match(regex);
    let numberOfItems = parseInt(numberOfItemsRaw);
    let item = args.join(' ').replace(numberOfItems, '').replace(' ', '');
     //if they don't specify a number assume one.
      if (numberOfItemsRaw === NaN || numberOfItemsRaw === null || numberOfItemsRaw === undefined) {
        numberOfItems = 1;
    }
    //because some idot is gonna put 0, i guarantee it
    if (numberOfItems === 0) {
        message.channel.send('ok karen');
        return;
    }
    //if item is not in the shop, then big oof
if (!Object.keys(itemCost).includes(item)) {
        message.channel.send("dude that's not an item in the shop");
        return;
    }
    //total cost
    let total = itemCost[item] * numberOfItems;
    //if ur broke
    if (total > await d.users.get(message.author.id)) {
        message.channel.send('you donut have enough money, rip');
        return;
    }
    //take money
    d.addMoni(message.author.id, -total)
    //intialize item property to store item
    if (have[item] === undefined || have[item] === null) {
    have[item] = 0;
    }
   //give item(s)
    have[item] += numberOfItems
   //put in db
    d.items.set(message.author.id, have);
    message.channel.send(item);
    message.channel.send(numberOfItems);
}
buy();
    }
};

How do I fix it so it doesn't return an undefined error?

Answer 1

You forgot to initialize have when await d.items.get(message.author.id) is null or undefined.

//get person's inventory
let have = await d.items.get(message.author.id);
//if they arent in the db, initialize
if (have === undefined || have === null) {
    await d.items.set(message.author.id, blankObj);
    have = blankObj; // <<
}

So that have won't be undefined when you try to evaluate have[item].