title: How to handle GoogleMap unavailable
body: <p><strong>Problem:</strong> <code>GoogleMap</code> is sometimes <code>null</code> (for reason's unknown to me).
  As far as I know this can happen when Google Play Services are not installed.</p>
  
  <p><strong>Question:</strong> </p>
  
  <ul>
  <li>Is there a way to know when the GoogleMap is or will be available (<code>!= null</code>). Is there a good way to handle this other than showing the user a "I'm sorry but the app could't load" message?</li>
  <li>Is there a way to know the reason why <code>GoogleMap</code> is <code>null</code>?</li>
  </ul>