title: XHR throws errors that can't be catched
body: <p>I'm using the <a href="https://www.npmjs.com/package/xhr" rel="nofollow">XHR</a> lib on npm to make ajax requests on the client-side of a JS application. My code looks like this:</p>
  
  <pre><code>xhr({uri: "http://foo"},function (err, resp, body){
      if (err) ...
      else ...
  });
  </code></pre>
  
  <p>Weirdly, even though I'm treating the errors on the callback, XHR still throws error messages such as <code>Failed to load resource: the server responded with a status of 503 ()</code>. Since those messages are thrown by callback, I can't catch them. <strong>How can I disable XHR's error messages?</strong></p>