title: React Native: app doesn't load, but no error messages, after installing react-navigation
body: <p>I followed all the steps in React Native's <a href="https://facebook.github.io/react-native/docs/getting-started" rel="nofollow noreferrer">get started</a> page, including running <code>npx react-native init AwesomeProject
  </code> to create a starter project. (I'm following the steps for "React Native CLI Quickstart" / "macOS" / "Android"). Then I open up Android Studio, start the emulator, cd into the project's folder, and run <code>npx react-native run-android</code>. Everything works fine. I get to tweak the starter project here and there, reload, and everything works. </p>
  
  <p>But I need to use React Navigation. I follow the steps <a href="https://facebook.github.io/react-native/docs/navigation" rel="nofollow noreferrer">here</a> and apparently React Navigation is installed without any issues. Then when I run <code>npx react-native run-android</code> again the thing builds successfully and that Metro thing - that separate Terminal tab/window - says "done". But the emulator doesn't show my app. For a second it shows a blank page and then that disappears and I get the emulator's home screen. That's even if I don't tweak the starter code at all - I'm not even trying to import React Navigation, all I need to do to cause this error is to have it installed.</p>
  
  <p>Here's what my Terminal tabs look like after <code>npx react-native run-android</code>:</p>
  
  <p><a href="https://i.stack.imgur.com/oAp4i.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/oAp4i.png" alt="enter image description here"></a></p>
  
  <p><a href="https://i.stack.imgur.com/PQZ82.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/PQZ82.png" alt="enter image description here"></a></p>
  
  <p>I've tried closing Terminal and Android Studio after installing React Navigation. Same thing.</p>
  
  <p>I'm using macOS 10.15.3 and Android Studio 3.5.3.</p>
  
  <p>What am I doing wrong?</p>