title: undefined is not an object ( evaluating '_expo.default.Constants')
body: <p>I would like to debug on my mobile/simulator and point it dynamically to API.</p>
  
  <pre><code>const {manifest} = Expo.Constants; 
  const api = manifest.packagerOpts.dev
  ? manifest.debuggerHost.split(':').shift().concat(':3000')
  : 'productionurl.com'
  
  
  export function getEvents(){
      return fetch('http://${api}/events')
      .then(response =&gt; response.json())
      .then(events =&gt; events.map(e =&gt;({ ...e, date: new Date(e.date)})));
  }
  </code></pre>
  
  <p>I am getting the following error:</p>
  
  <blockquote>
    <p>undefined is not an object(evaluating'_expo.default.Constants')</p>
  </blockquote>