title: Issue accessing event.nativeEvent.layout.x in react native /w expo
body: <p>So I'm simply trying to access the x coordinate through the onLaypout prop within a TouchableOpacity component in react native and I'm getting an error in the emulator saying</p>
  <pre><code>null is not an object (evaluating 'event.nativeEvent.layout')
  </code></pre>
  <p>This is my first time dabbling into the react animation side of things and have no idea why it's failing. There also doesn't seem to be much online about it so I'm starting to think it's been deprecated.</p>
  <pre><code>&lt;TouchableOpacity 
     onLayout={(event) =&gt; this.setState(prevState =&gt; ({ 
         tabs: { ...prevState.tabs, xTabOne: event.nativeEvent.layout.x } 
     }))}
  /&gt;
  </code></pre>
  <p>Any help would be great,
  Chris.</p>