title: Promise All is causing a 204 response
body: <p>During my page load I am trying to load two datasets.</p>
  
  <p>Both of these load on a <code>Promise</code> so I have been trying to use <code>Promise.all</code></p>
  
  <p>Unfortunately when I use this technique I get a <code>204</code> for my <code>request.status</code></p>
  
  <p>Notes: </p>
  
  <ul>
  <li>These requests are using <code>XMLHttpRequest</code> not <code>fetch</code></li>
  <li>They are plain <code>GET</code> requests</li>
  <li>They work fine in isolation</li>
  </ul>
  
  <p>Here is the code as a <code>Promise.all</code></p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>let p1 = dataLibrary.asyncStoreList();
  let p2 = dataLibrary.asyncGetAllResults(2);
  
  Promise.all([p1, p2]).then(([{stores,data}]) =&gt; {
    buildAverageByStore(stores, data);
    // ... More code
  });</code></pre>
  </div>
  </div>
  </p>
  
  <p>If I chain the <code>Promises</code> it works fine:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>let stores, data;
  dataLibrary.asyncStoreList().then(s =&gt; {
    stores = s.map(store =&gt; {
      store.speed = {};
      return store;
    });
    dataLibrary.asyncGetAllResults(2).then(d =&gt; {
      data = d;
      buildAverageByStore(stores, data);
    });
  });</code></pre>
  </div>
  </div>
  </p>
  
  <p>Anyone else seen this behavior, am I missing something simple?</p>