title: Corda /upload/attachment using fetch api gets correct response in network but throws error
body: <p>I'm trying to attach a document to my node. I have the following code in React.</p>
  
  <pre><code>const url = `http://localhost:10015/upload/attachment`;
  const formData = new FormData();
  formData.append('file',file); // from file select
  let result = await fetch(url, {
    method: 'post',
    body: formData
  });
  </code></pre>
  
  <p>When I view the network logs, it looks like there isn't an issue<a href="https://i.stack.imgur.com/vrzWb.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/vrzWb.jpg" alt="enter image description here"></a></p>
  
  <p>And the response is the hash of the attachment.</p>
  
  <p>When I view the logs, I have this error:</p>
  
  <p><a href="https://i.stack.imgur.com/GH3tV.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GH3tV.jpg" alt="enter image description here"></a></p>
  
  <p>Could anyone help me out with this? </p>