message: Used && conditional render techinque
diff: @@ -52,11 +52,9 @@ class NavigationMotion extends React.Component {
  }
  render() {
  var {oldState, oldData, state, data, crumbs, nextCrumb} = this.getStateNavigator().stateContext;
  - if (!state)
  - return null;
  var {unmountedStyle, style, children} = this.props;
  var sceneContexts = crumbs.concat(nextCrumb);
  - return (
  + return (state &&
  <TransitionMotion
  willEnter={() => getStyle(unmountedStyle, state, data, true)}
  willLeave={() => getStyle(unmountedStyle, oldState, oldData)}
  