title: How to fix the console warning "The resource ... was preloaded using link preload but not used within a few seconds from the window's load event"?
body: <p>I'm developing a gatsby theme/starter for PWA's, but I can't seem to get rid of the following console warning:</p>
  
  <pre><code>The resource https://davidde.github.io/gatsby-starter-simpwa/page-data/offline-plugin-app-shell-fallback/page-data.json
  was preloaded using link preload but not used within a few seconds from the window's load event.
  Please make sure it has an appropriate `as` value and it is preloaded intentionally.
  </code></pre>
  
  <p>On first load everything works fine; the service worker registers like it should and there is no warning. However, after reloading, this warning shows up. This makes no sense since the <code>as</code> value is set to 'fetch'.
  I'm assuming it has something to do with the configuration of <code>gatsby-plugin-offline</code> or maybe <code>gatsby-plugin-manifest</code>.  </p>
  
  <p>The source code is at <a href="https://github.com/davidde/gatsby-starter-simpwa" rel="noreferrer">https://github.com/davidde/gatsby-starter-simpwa</a>,<br>
  and it's deployed to <a href="https://davidde.github.io/gatsby-starter-simpwa/" rel="noreferrer">https://davidde.github.io/gatsby-starter-simpwa/</a>.</p>
  
  <p>Does anyone have any idea what is causing this? </p>