(node:65297) UnhandledPromiseRejectionWarning: TypeError: mem.addRole is not a function

i am having an issue with a Run script. I am using Discord Bot Maker for JavaScript code with run script in it. As you can see, this is a Persistent Role system. It is supposed to keep your roles, if you leave the discord server, and give them back if you return. But once I upgraded to discord.js V12 i have gotten this error, and can't figure out how to fix it. Does anyone have an idea?

const roles = tempVars("roles");
const arr = roles.split(',');
const guild = client.guilds.cache.get(tempVars("serv_id"));
const mem = tempVars("mem");

if (!roles) console.error('Role list is undefined, cant add roles.');

(async () => {
    for (var i = 0; i < arr.length; i++) {
        let elm = arr[i];
        if (elm !== "@everyone") {
            elm = elm.replace('<@&', '')
                .replace('>', '');
            mem.addRole(elm)
                .catch(console.error);
            await require('util')
                .promisify(setTimeout)(1000)
        }
    }
console.log(`Added all applicable roles to ${mem.user.tag}`);
Actions.callNextAction(cache);
})()

In version 12 <member>.addRole() has been replaced by <member>.roles.add()

Try changing mem.addRole(elm) to mem.roles.add(elm)