title: TapGestureHandler not triggering onHandlerStateChange
body: <p>I have a <code>onHandlerStateChange</code> event in <code>TapGestureHandler</code>. When the onHandlerStateChange is triggered, i want to change the opacity of a button inside <code>TapGestureHandler</code>.</p>
  
  <pre><code>&lt;View style={{ height: height / 3, justifyContent: 'center' }}&gt;
    &lt;TapGestureHandler onHandlerStateChange={ this.onStateChange }&gt;
      &lt;Animated.View 
          style={{ ...styles.button, opacity: this.buttonOpacity }}&gt;
        &lt;Text style= {{ fontSize:16, fontWeight: 'bold' }}&gt;GET STARTED&lt;/Text&gt;
      &lt;/Animated.View&gt;
    &lt;/TapGestureHandler&gt;        
  &lt;/View&gt;
  </code></pre>
  
  <p>And inside <code>this.onStateChange</code> i have the following codes to change the opacity.</p>
  
  <pre><code>constructor(props) {
      super(props);
      this.state={
      }
      this.buttonOpacity = new Value(1)
      this.onStateChange = event([{
        nativeEvent: ({ state }) =&gt; 
        block([
          cond( eq(state, State.END), set(this.buttonOpacity, 0) )
        ])
      }])
    }
  </code></pre>
  
  <p>Im using android studio emulator and trying to run android app using <code>react-native run-android</code> and also imported </p>
  
  <pre><code>import Animated from 'react-native-reanimated'
  import {TapGestureHandler, State} from 'react-native-gesture-handler'
  </code></pre>
  
  <p>Im a beginner to react native programming.</p>