Discord.js - Get a random user with a reaction

So I made a giveaway and I want to get a random user who reacts to 🎉, but it didn't work.

bot.channels.get(giveawayChannelid).fetchMessage(messageID)
    .then(message => {  
      let reaction = message.reactions.find(r => r.emoji.name == '🎉');
  if (reaction) {
      var randomUser = reaction.users.random(1);
   }
  });