[Bug]: onLocation is triggered with no coords in locations but is defined in the Location type

[cizar]

Required Reading

• Confirmed

Plugin Version

4.18.8

Mobile operating-system(s)

• iOS
• Android

Device Manufacturer(s) and Model(s)

iPhone 12 iOS 18.1 on Simulator

Device operating-systems(s)

iOS 18.1

React Native / Expo version

expo 53.0.19

What happened?

Although coords is defined to be present in location, it is sometimes undefined. There is no clear pattern. I left the app running with "City Bicycle Ride" for a while, and sometimes it happens. In my app, I had to verify that the coords were set before using it.

// A part of a zustand useLocationStore that keep all time the latest location
locationSubscription = BackgroundGeolocation.onLocation((location) => {
  if (!location.coords) {
    console.warn("Received location without coordinates:", location); // {"error": 0}
    return;
  }
  set({ currentLocation: location });
});

It's like the success callback is being executed with an error code

    static onLocation(success: (location:Location)=>void, failure?:(errorCode: LocationError) => void):Subscription;

Plugin Code and/or Config

export function initGeolocation() {
  return BackgroundGeolocation.ready({
    desiredAccuracy: BackgroundGeolocation.DESIRED_ACCURACY_HIGH,
    distanceFilter: 50,
    stopOnTerminate: false, // Continue tracking even if the app is terminated.
    startOnBoot: true, // Restart tracking when the device restarts.
    enableHeadless: true, // Support for background service when app is not active.
    locationAuthorizationRequest: "Always",
    foregroundService: true,
  });
}

Relevant log output

[christocracy]

See the api docs .onLocation and provide the 2nd argument onErrorCallback.

If you don’t provide the 2nd arg, location errors will be sent the 1st arg callback.

[cizar]

I'm confused by the callback type definition, but I checked the documentation and it's clearer now. Perhaps method overloading would make it more intuitive, like...

type SuccessHandler = (location: Location) => void;
type ErrorHandler = (error: LocationError) => void;
type UnifiedHandler = (locationOrError: Location | LocationError) => void;

class BackgroundGeolocation {
  static onLocation(handler: UnifiedHandler): Subscription;
  static onLocation(success: SuccessHandler, failure?: ErrorHandler): Subscription {
    // ...
  }
}

[christocracy]

.onLocation((location) => {
  console.log(“location: ”, location);
}, ((error) => {
  console.log(“error: “, error);
});