Division by null error when moving map's center

[bramvbilsen]

I am trying to move the center of a map whenever I retrieve the user's location.
I have the following code to do that:

void initState() {
  super.initState();
  mapController = new MapController();
  try {
    new Location().getLocation.then((Map<String, double> loc) {
      print(loc);
      print("Map ready: " + mapController.ready.toString());
      setState(
          () => location = new LatLng(loc["latitude"], loc["longitude"]));
      mapController.move(location, zoom); // Location and zoom are not null
    })/*.catchError((e) => print(e))*/;
  } catch (e) {
    print(e);
    showDialog(
        context: context,
        builder: (BuildContext context) {
          return new Center(
            child: new Text("We couldn't get your location!"),
          );
        });
  }
}

Doing this, I'm getting the following error:

I/flutter (21207): {altitude: 3.40031719, latitude: 33.985311, accuracy: 11.723999977111816, speed_accuracy: 0.0, speed: 0.0, longitude: -118.2043953}
E/flutter (21207): [ERROR:topaz/lib/tonic/logging/dart_error.cc(16)] Unhandled exception:
E/flutter (21207): NoSuchMethodError: The method '/' was called on null.
E/flutter (21207): Receiver: null
E/flutter (21207): Tried calling: /(2.0)
E/flutter (21207): #0      Object.noSuchMethod (dart:core/runtime/libobject_patch.dart:46:5)
E/flutter (21207): #1      MapState.getNewPixelOrigin (package:flutter_map/src/map/map.dart:187:30)
E/flutter (21207): #2      MapState.move (package:flutter_map/src/map/map.dart:85:20)
E/flutter (21207): #3      MapControllerImpl.move (package:flutter_map/src/map/map.dart:23:12)
E/flutter (21207): #4      MapViewState.initState.<anonymous closure> (file:///C:/Users/bramv/Documents/Yes%20Theory/map_test/lib/main.dart:390:23)
E/flutter (21207): #5      _RootZone.runUnary (dart:async/zone.dart:1381:54)
E/flutter (21207): #6      _FutureListener.handleValue (dart:async/future_impl.dart:129:18)
E/flutter (21207): #7      Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:638:45)
E/flutter (21207): #8      Future._propagateToListeners (dart:async/future_impl.dart:667:32)
E/flutter (21207): #9      Future._complete (dart:async/future_impl.dart:472:7)
E/flutter (21207): #10     _SyncCompleter.complete (dart:async/future_impl.dart:51:12)
E/flutter (21207): #11     _AsyncAwaitCompleter.complete (dart:async/runtime/libasync_patch.dart:28:18)
E/flutter (21207): #12     MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart)
E/flutter (21207): <asynchronous suspension>
E/flutter (21207): #13     Location.getLocation (package:location/location.dart:12:8)
E/flutter (21207): #14     MapViewState.initState (file:///C:/Users/bramv/Documents/Yes%20Theory/map_test/lib/main.dart:386:22)
E/flutter (21207): #15     StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3764:58)
E/flutter (21207): #16     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
E/flutter (21207): #17     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
E/flutter (21207): #18     MultiChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4772:32)
E/flutter (21207): #19     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
E/flutter (21207): #20     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
E/flutter (21207): #21     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
E/flutter (21207): #22     Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
E/flutter (21207): #23     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
E/flutter (21207): #24     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
E/flutter (21207): #25     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
E/flutter (21207): #26     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
E/flutter (21207): #27     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4667:14)
E/flutter (21207): #28     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
E/flutter (21207): #29     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
E/flutter (21207): #30     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
E/flutter (21207): #31     Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
E/flutter (21207): #32     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
E/flutter (21207): #33     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
E/flutter (21207): #34     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
E/flutter (21207): #35     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
E/flutter (21207): #36     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
E/flutter (21207): #37     Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
E/flutter (21207): #38     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
E/flutter (21207): #39     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
E/flutter (21207): #40     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
E/flutter (21207): #41     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
E/flutter (21207): #42     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
E/flutter (21207): #43     Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
E/flutter (21207): #44     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
E/flutter (21207): #45     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
E/flutter (21207): #46     ParentDataElement.mount

I also checked whether the map controller is ready and it is.
I used the following code to create the map:

new FlutterMap(
            mapController: mapController,
            options: new MapOptions(
              center: fallbackLocation,
              zoom: zoom,
            ),
            layers: [
              new TileLayerOptions(
                urlTemplate: "https://api.tiles.mapbox.com/v4/"
                    "{id}/{z}/{x}/{y}@2x.png?access_token=...",
                additionalOptions: {
                  'accessToken':
                      '<...>',
                  'id': 'mapbox.streets',
                },
              ),
              new MarkerLayerOptions(
                  markers: location == null
                      ? []
                      : [
                          new Marker(
                            width: 40.0,
                            height: 40.0,
                            point: location,
                            builder: (ctx) => new Container(
                                  child: new Icon(
                                    Icons.add_location,
                                    color: Colors.redAccent,
                                    size: 40.0,
                                  ),
                                ),
                          )
                        ]),
            ]),

Any reason why this would fail?

[maral]

I recently got very similar error, yet I can't tell what is wrong with your code. Apparently some supplied argument to MapState.getNewPixelOrigin() is null (although possibly not from you).

I solved my problem by debugging and setting breakpoint right before the exception was thrown to MapState.getNewPixelOrigin function. Then I traced which method first introduced invalid argument. In my case, the invalid point came from me not setting the height of the parent widget of the map.

[johnpryan]

ah I see. Glad you found the issue! Maybe the map widget could throw some exception if it detects an invalid widget size.

[bramvbilsen]

I haven't looked at it since I posted the issue but I did debug it and I believe size was null which causes the error. I am not sure why it'd be null though.

[johnpryan]

Marking as an enhancement so we do better checking up-front to throw better errors

[johnpryan]

I think this issue is stale