Flutter app error "NoSuchMethodError: The getter 'length' was called on null" - api

Question

Am getting this error and can't find the why, the app shows a google map calling hospital from google map places api, api call returns fine when used in chrome, but the app fail to build showing the "NoSuchMethodError: The getter 'length' was called on null" error. Thanks for your help.
class Search extends StatelessWidget {
#override
Widget build(BuildContext context) {
final currentPosition = Provider.of<Position>(context);
final placesProvider = Provider.of<Future<List<Place>>>(context);
return FutureProvider(
create: (context) => placesProvider,
child: Scaffold(
body: (currentPosition != null)
? Consumer<List<Place>>(
builder: (_, places, __) {
return Column(
children: <Widget>[
Container(
height: MediaQuery.of(context).size.height / 3,
width: MediaQuery.of(context).size.width,
child: GoogleMap(
initialCameraPosition: CameraPosition(
target: LatLng(currentPosition.latitude,
currentPosition.longitude),
zoom: 16.0),
zoomGesturesEnabled: true,
mapToolbarEnabled: true,
myLocationEnabled: true,
scrollGesturesEnabled: true,
),
),
SizedBox(
height: 10.0,
),
Expanded(
child: ListView.builder(
itemCount: places.length,
itemBuilder: (context, index) {
return Card(
child: ListTile(
title: Text(places[index]?.name),
),
);
}),
)
],
);
},
)
: Center(
child: CircularProgressIndicator(),
),
),
);
}
}
The api request works fine when called in chrome, problem is when building the app. This is my places_service.dart file:
class PlacesService {
final key = 'xxxxxxxxxxxxxxxxxxxxx-ttttttttttttttttt';
Future<List<Place>> getPlaces(double lat, double lng) async {
var response = await http.get('https://maps.googleapis.com/maps/api/place/nearbysearch/json?location=$lat,$lng&type=hospital&rankby=distance&key=$key');
var json = convert.jsonDecode(response.body);
var jsonResults = json['results'] as List;
return jsonResults.map((place) => Place.fromJson(place)).toList();
}
}
Problem is this line:
itemCount: places.length,

Answer 1

If you use constructions like places.length the programming code can fail on two places:
when places = null
when places.length = null (your situation)
You cannot call methods and properties on null-objects; that is why you get this error. So before you call places.length you must be sure that both situations cannot occur. How this is done and if the check is really necessary depends on the rest of your program. One way to check is:
itemCount: places.length != null ? places.length : 0;