title: How to check if users id = any id in JSON file?
body: <p>I tried to take data from a JSON file where someone &quot;who typed the message&quot; has his information with his id inside. There was nothing inside the JSON file, so it gave me error.</p>
  <p>How do I set to that if we get an error then reply something like &quot;you have not set anything&quot;. Or set that by the best way, that means check for ids of author.
  The code I tried (<code>_message</code> goes inside tradeLinks folder):</p>
  <pre><code>let _message = client.tradeLinks[message.author.id].tradelink;
  if (_message = err) {
    message.reply('You have not set the trade-link !');
  }
  </code></pre>