title: React native Android SyntaxError: Attempted to redefine property 'key'
body: <p>I get the following error on Emulators (tested Genymotion and google Stock Emulator) and on a physical device (Samsung S4) after running <code>react-native run-android</code>:</p>
  
  <p><a href="https://i.stack.imgur.com/M1MS5.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/M1MS5.png" alt="enter image description here"></a></p>
  
  <p>The error typed out:
  <code>
  java.util.concurrent.ExcecutionException: java.lang.RuntimeException: SyntaxError: Attempted to redefine property 'key'. (http://192.168.50.37:8081/index.android.bundle?platform=android&amp;dev=true&amp;hot=false:72450)
  </code></p>
  
  <ul>
  <li>In <a href="https://stackoverflow.com/questions/36133563/react-native-with-genymontion-throwing-concurrent-exception">this stackoverflow discussion</a> a similar error (also an <code>java.util.concurrent.ExecutionException</code>) occurred with Genymotion but the solution there didn't help me, i.e. <code>adb reverse tcp:8081 tcp:8081</code>.</li>
  <li>I also tried changing Dev Settings/<code>Debug server host &amp; port for device</code> to <code>0.0.0.0:8081</code> instead of <code>MY_IP:8081</code>, where <code>MY_IP</code> is the IP of my PC.</li>
  </ul>
  
  <p>I'm running react native 0.22.2</p>