title: React-native, "Native module cannot be null"
body: <p>I just upgrade React-native from 0.28 to 0.30, and get this error: </p>
  
  <p>"Native module cannot be null". </p>
  
  <p>The problem seem to be with the line/package: </p>
  
  <pre><code>var PushNotification = require('react-native-push-notification');
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/1tq3k.png" rel="noreferrer"><img src="https://i.stack.imgur.com/1tq3k.png" alt="Screenshot"></a></p>