title: Weird "Receiver not registered" exception
body: <p>In onResume() I do:</p>
  
  <pre><code>registerReceiver(timeTickReceiver, new IntentFilter(Intent.ACTION_TIME_TICK));
  </code></pre>
  
  <p>and in onPause():</p>
  
  <pre><code>unregisterReceiver(timeTickReceiver);
  </code></pre>
  
  <p>I see "java.lang.IllegalArgumentException: Receiver not registered" reports in Android Developer Console (there are only 2 reports and my app has thousands of users). The exception is triggered by unregisterReceiver(). What can be happening? I don't feel very confident to just surround it with try-catch.</p>