title: React Navigation blank screen
body: <p>I recently updated my Expo app to React Navigation 1.0.0-beta.19. Since then, it has been showing me only white screen. What can be the issue?</p>
  
  <p>Here is the snack for reproduction.
  <a href="https://snack.expo.io/@rajat1saxena/react-navigation-test" rel="nofollow noreferrer">https://snack.expo.io/@rajat1saxena/react-navigation-test</a></p>
  
  <p>Screen:
  <a href="https://i.stack.imgur.com/jcMU4.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/jcMU4.png" alt="enter image description here"></a></p>