Some errors are ignored and not provided to the client in completion handlers

[johnnewman]

Using v0.10.0 or v0.10.1, if you try to reverse geocode in airplane mode, the completion handler is never called. This can be replicated using the following code:

MBGeocoder *geocoder = [[MBGeocoder alloc] initWithAccessToken:<token>];
MBReverseGeocodeOptions *options = [[MBReverseGeocodeOptions alloc] initWithCoordinate:anyCoordinate];
[geocoder geocodeWithOptions:options completionHandler:^(NSArray<MBGeocodedPlacemark *> * _Nullable placemarks, NSString * _Nullable attribution, NSError * _Nullable error) {
        
    // never hit with an error
      
}];

This line

MapboxGeocoder.swift/MapboxGeocoder/MBGeocoder.swift

Line 271 in 4365b4c

guard let data = data else { return }

appears to be the culprit.

return URLSession.shared.dataTask(with: request) { (data, response, error) in

    guard let data = data else { return }
    ...

It returns immediately but the error object containing information about the network issue is ignored. Reproduced on iOS 12.0 and 12.1.

[1ec5]

I can reproduce this issue with any scenario that would result in a dataless response. By comparison, the analogous MapboxDirections.swift code is more robust, because the Directions API has a few such known edge cases: mapbox/mapbox-directions-swift#314.

/~https://github.com/mapbox/MapboxDirections.swift/blob/aa0e64bc10f1419b656c1fdae117a7c0d5f255b3/MapboxDirections/MBDirections.swift#L252-L258

[1ec5]

#175 has a fix for this issue.