class Peta extends StatefulWidget {
    _PetaState createState() => _PetaState();}

class _PetaState extends State<Peta> {
  Completer<GoogleMapController> _controller = Completer();

  void initState() {super.initState();}
  void _onMapCreated(GoogleMapController controller) {_controller.complete(controller);}

 Widget build(BuildContext context) {
  return Scaffold(
   appBar: AppBar(title: Text("PETA"),backgroundColor: Colors.lightGreenAccent[700],)
   body: Stack(children: <Widget>[_peta(context),])
  )
 }

 Widget _peta(BuildContext context) {
  return Container(height: MediaQuery.of(context).size.height, width: MediaQuery.of(context).size.width,
   child: GoogleMap(onMapCreated: _onMapCreated, mapType: MapType.normal,
    initialCameraPosition: CameraPosition(target: LatLng(-1.265386, 116.831200), zoom: 14),
    markers: {marker1, marker2},
   )
  );
 }
}

Marker marker1 = Marker(markerId: MarkerId("TOKO 1"), position: LatLng(-1.277025, 116.829049),
 infoWindow: InfoWindow(title: "TOKO MAKMUR"),
 icon: BitmapDescriptor.defaultMarkerWithHue(BitmapDescriptor.hueGreen,),
 onTap: () {
  showModalBottomSheet(
   context: context, /// this line is error
   builder: (builder){return Container(......)}
  );
 }
)