Discord.js Per Server Prefix Error "TypeError: Cannot read property 'ID' of null"

Hi i was making a per server prefix thing for my discord.js v12 bot using quick.db everything was going well but when using a command it throws this error

C:\Users\Aoshey\Desktop\Taco Bot V2\tacobot.js:50
        let prefix = db.get(`prefix_${message.guild.ID}`);

TypeError: Cannot read property 'ID' of null

i don’t quite understand since i’m new to coding so sorry if it was something stupid
the main bot file’s code:

client.on('message', message => {
	let prefix = db.get(`prefix_${message.guild.ID}`);
	if(prefix === null) prefix = default_prefix;
	if (!message.content.startsWith(prefix) || message.author.bot) return;

	const args = message.content.slice(prefix.length).trim().split(/ +/);
	const commandName = args.shift().toLowerCase();

	const command = client.commands.get(commandName)
		|| client.commands.find(cmd => cmd.aliases && cmd.aliases.includes(commandName));

	if (!command) return;

	if (command.guildOnly && message.channel.type === 'dm') {
		return message.reply('I can\'t execute that command inside DMs!');

	if (command.args && !args.length) {
		let reply = `${message.author}, wrong usage`;

		if (command.usage) {
			reply += `\nThe proper usage would be: \`${prefix}${command.name} ${command.usage}\``;

		return message.channel.send(reply);

	try {
		command.execute(message, args);
	} catch (error) {
		message.reply('there was an error trying to execute that command! Please tell Aro#1221 about this.');

EDIT: i noticed that the error only occurs when its used on only 1 command meanwhile other commands work well
the code for the command which causes the error i think?

const fsn = require("fs-nextra");
const colors = require("colors");

module.exports = {
    name: 'deleteorder',
    description: 'deleting/denying an order.',
    args: 'true',
    usage: '<order id> <reason>',
    aliases: ['od', 'delorder', 'do'],
    execute(message, args) {

        if (message.member.roles.cache.find(r => r.id === '745410836901789749')) {
            let ticketID = args[0];
            let reason = args[1];

            fsn.readJSON("./orders.json").then((orderDB) => {
                const order = orderDB[ticketID];

                if(order === undefined) {
                    message.reply(`Couldn't find order \`${args[0]}\` Try again.`);


                if(reason === "") {
                    reason = "None Provided";

                delete orderDB[ticketID];

                fsn.writeJSON("./orders.json", orderDB, {
                    replacer: null,
                    spaces: 4

                message.reply(`You deleted order \`${args[0]}\` with reason \`${args[1]}\``)
                // Sends a message to the customer.
                let customer = message.guild.members.cache.find(m => m.id === order.userID)
                //message.users.cache.get(order.userID).send(`Sorry, but your order was cancelled by **${message.author.username}** due to the following reason: \`${reason}\`.`);
                customer.send(`Sorry, but your order was cancelled by **${message.author.username}** due to the following reason: \`${reason}\`.`)

                // Logs in console.
                console.log(colors.red(`${message.author.username} deleted order ${order.orderID}.`));


        } else {
            message.reply("You aren't an employee.");
            console.log(colors.red(`${message.author.username} did not have access to the delorder command.`));

Are you using this command in dms? message.guild will only exist if it was sent in a server. I’ve got no idea why other commands are working though.

no i’m not i was using it in a guild