title: Discord.js v13 sending buffer as attachment results in invisible image
body: <p>I'm trying to send a buffer as an attachment in Discord.js v13.
  I'm using the same code that worked in v11, with the necessary syntax changes to v13.</p>
  <p>The image at the specified path does exist and if I save the buffer to my disk as an image, it works just fine.<br>
  If I send it as an attachment in Discord it results in an empty attachment like this:</p>
  <p><a href="https://i.stack.imgur.com/7qseV.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/7qseV.png" alt="Empty attachment" /></a></p>
  <p>This is my code:</p>
  <pre class="lang-js prettyprint-override"><code>const promise = fs.promises.readFile(path.join('./assets/Environment/Base.png')); //this image exists
  
  Promise.resolve(promise).then(function(buffer){
      message.channel.send({content: `${message.author.username}'s base:\n⁣`, attachment: [buffer]}).catch(allerrors)
  });
  </code></pre>
  <p>I asked in several Discord servers, but nobody was able to help me so I thought I'd ask here, does anyone know what could be causing this?<br>
  Thanks!</p>