botSnippet05.js

...
if (data && 'players' in data) {
  const { user } = message;
  const { players } = data;

  if (user in players && !players[user].accepted) {
    // player two accepted
    bot.reply(message, 'GREAT, LET THE BATTLE BEGIN!!!');
  } else {
    const player = Object.keys(players).find((p) => !players[p].accepted);
    bot.reply(message, `Not you <@${user}>, waiting for <@${player}>.`);
  }
}