title: async SetState in componentDidMount() warning in React Native
body: <p>The warning message says: </p>
  
  <p>"Warning: Can only update a mounted or mounting component. This usually means you called setState, replaceState, or forceUpdate on an unmounted component. This is a no-op."</p>
  
  <p>The code caused it:</p>
  
  <pre><code>async componentDidMount() {
    const token = await AsyncStorage.getItem('google_token');
  
    if (token) {
      this.props.navigation.navigate('feed');
      this.setState({ token });
    } else {
      this.setState({ token: false });
    }
   }
  </code></pre>
  
  <p>After some google, I'm really confused on if I should be worried about this warning. How can I get the warning message away without disabling the rule like this <a href="https://github.com/airbnb/javascript/issues/684" rel="nofollow noreferrer">Github issue</a> suggested ?</p>