geolocation.watchPosition() - subscription.listener.apply is not a function

Environment

• React Native 0.31.0
• OSX 10.11.6
• iOS Emulator 9.6 (doesn’t happen on Android)

The code

class MyComponent extends Component {
  constructor() {
    super();
    this.state = {};
  }

  componentDidMount() {
    this.watcher = navigator.geolocation.watchPosition(
      pos => this.setState(pos.coords);
    );
  }

  componentWillUnmount() {
    navigator.geolocation.clearWatch(this.watcher);
  }

  render() {
    return (
      <Text>{this.state.latitude}</Text> 
    );
  }
}

Steps to reproduce

1. Load the app in an iOS emulator (9.6). Coords load fine.
2. Change the location Debug -> Location -> …. Coords load fine.
3. Change the location again. You should see: subscription.listener.apply is not a function

[jschloer]

For people encountering this later… I ran into this as well because I passed a position options object without an error handler. If you do so, the eventEmitter will try to run your options object as the error handler function. Also, this means that your options aren’t being processed properly without an error handler, so if you need to send options to watchPosition, make sure to send the semi-optional error handler as well.

[facebook-github-bot]

@charpeni tells me to close this issue. If you think it should still be opened let us know why.