title: addRole is not a function
body: <p>I am creating a Discord Bot.
  I am trying create a Mute command, but I always get the same error.</p>
  
  <p><a href="https://i.stack.imgur.com/NyC0w.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/NyC0w.png" alt="enter image description here"></a></p>
  
  <p>What went wrong?</p>
  
  <p>Background information:</p>
  
  <ul>
  <li><p>Discord.js version: <code>12.0.0-dev</code></p></li>
  <li><p>Klasa with version <code>0.5.0-dev</code> is used</p></li>
  </ul>
  
  <p>Code:</p>
  
  <pre><code>const { Command } = require('klasa');
  const { MessageEmbed } = require('discord.js');
  
  module.exports = class extends Command {
  
      constructor(...args) {
          super(...args, { description: 'Mute an user.' })
      }
  
      async run(msg, args) {
          if(!msg.member.hasPermission("MANAGE_MEMBERS")) return msg.channel.send("You can't use this command.");
  
          let MuteUser = msg.guild.member(msg.mentions.users.first() || msg.guild.members.get(args[0]))
          if(!MuteUser) return msg.channel.send("Can't find user!");
  
          let MuteReason = msg.content.split(" ").slice(2).join(" ");
  
          let MuteRole = msg.guild.roles.find(r =&gt; r.name === "Spammer");
          if(!MuteRole) return msg.channel.send("Can't find the Spammer role!");
  
          let MuteChannel = msg.guild.channels.find(guild =&gt; guild.name === 'bot-logs');
          if(!MuteChannel) return msg.channel.send("Can't find the #bot-logs channel.");
  
          if(MuteUser.roles.has(MuteRole)) return msg.channel.send("That user is already muted!.");
  
          MuteUser.addRole(MuteRole.id);
  
          return MuteChannel.send(new MessageEmbed()
              .setAuthor("Mute"|| 'Unknown', "http://wolfdevelopment.cf/BotSymbols/info.png")
              .setColor("#ff0000")
              .addField("Muted User", `${MuteUser}`)
              .addField("Muted By", `&lt;@${msg.author.id}&gt;`)
              .addField("Muted In", `${msg.channel}`)
              .addField("Time", `${msg.createdAt}`)
              .addField("Reason", `${MuteReason}`));
      }
  }
  </code></pre>
  
  <p>I have checked that <code>MuteUser</code> is a person in this line:</p>
  
  <pre><code>    if(!MuteUser) return msg.channel.send("Can't find user!");
  </code></pre>
  
  <p>So it must be a person. Why doesn't it have an <code>addRole</code> function?</p>