title: React-Navigation and TypeScript. Property 'getScreen' is missing in type
body: <p>Using TypeScript and react-navigation is get the following TypeScript issue:</p>
  
  <pre><code>  Property 'Principles' is incompatible with index signature.
      Type '{ screen: (props: any) =&gt; Element; path: string; }' is not assignable to type 'NavigationRouteConfig'.
        Type '{ screen: (props: any) =&gt; Element; path: string; }' is not assignable to type '{ navigationOptions?: any; path?: string; } &amp; { getScreen: () =&gt; NavigationComponent; }'.
          Type '{ screen: (props: any) =&gt; Element; path: string; }' is not assignable to type '{ getScreen: () =&gt; NavigationComponent; }'.
            Property 'getScreen' is missing in type '{ screen: (props: any) =&gt; Element; path: string; }'.
  </code></pre>
  
  <p>Here is the code in my  navigator:</p>
  
  <pre><code>const MainNavigator: NavigationContainer = StackNavigator({
      Principles: {
        screen: props =&gt; &lt;WebViewModal source={{ uri: MY_URI }} {...props} /&gt;,
        path: 'principles',
      },
  })
  </code></pre>
  
  <p>And that is the code of the <code>WebViewModal</code>:</p>
  
  <pre><code>export interface IWebViewModalProps extends WebViewProperties, NavigationScreenProps {}
  
  class WebViewModal extends Component&lt;IWebViewModalProps&gt; {
    closeModal = () =&gt; {
      this.props.navigation.goBack();
    };
  
    render() {
      const {...props } = this.props;
      return (
        &lt;View style={styles.container}&gt;
          &lt;TopNavigationBar left={&lt;Icon name="close" onPress={this.closeModal} /&gt;} /&gt;
          &lt;WebView {...props} /&gt;
        &lt;/View&gt;
      );
    }
  }
  
  export default WebViewModal;
  </code></pre>
  
  <p>How can I fix this typescript issue?</p>