Discord.js v12 Role add to mentioned user problem - discord.js

Question

so I am trying to make a command like $roletested #user which should give the user mentioned the specific role. I get an error called:_ "Cannot read property 'roles' of undefined... Help me out please, here's my code :D
if (message.content.startsWith(prefix + "roletested")) {
let testedUser = message.mentions.members.first()
if (!message.member.hasPermission('MANAGE_ROLES')) return message.channel.send('You do not have that permission! :x:').then(message.react(':x:'));
if(!testedUser) return message.channel.send("You have to mention the person you want to assign the role to!").then((declineMsg) => { message.react('❌');
declineMsg.delete({timeout: 5000});
let testedRole = message.guild.roles.cache.find(role => role.id === "724676382776492113");
testedUser.roles.add(testedRole);
message.channel.send("Added the role `TESTED` to user.")
})}})

Answer 1

Your code but fixed
if (message.content.startsWith(prefix + "roletested")) {
if (!message.member.hasPermission('MANAGE_ROLES')) return message.channel.send('You do not have that permission! :x:').then(message.react(':x:'))
let testedRole = message.guild.roles.cache.get('724676382776492113');
let testedUser = message.mentions.members.first();
if(!testedUser) return message.channel.send("You have to mention the person you want to assign the role to!").then((declineMsg) => { message.react('❌')
declineMsg.delete({timeout: 5000});
});
testedUser.roles.add(testedRole);
message.channel.send("Added the role `TESTED` to user.")
}

Answer 2

I fixed your code :
I put in order something (the code is the same, I only changed something)
You can't use message.guild.roles.cache.find(...) so I changed it to message.guild.role.cache.get('Role ID')
Source : Link
Code :
if (message.content.startsWith(prefix + 'roletested')) {
const testedUser = message.mentions.members.first();
if (!message.member.hasPermission('MANAGE_ROLES')) return message.channel.send('You do not have that permission! :x:').then(message.react(':x:'));
if (!testedUser) {
message.channel.send('You have to mention the person you want to assign the role to!').then(declineMsg => {
message.react('❌');
declineMsg.delete({ timeout: 5000 });
return;
});
}
const testedRole = message.guild.roles.cache.get('395671618912780289');
testedUser.roles.add(testedRole);
message.channel.send('Added the role `TESTED` to user.');
}
I tested this code on my bot and it worked as expected.