update: make OSM widget stateftul

app/lib/widgets/osm_layer.dart

@@ -4,7 +4,7 @@ import 'package:flutter_map/flutter_map.dart';
 
 import '../data_classes.dart';
 
-class OSM extends StatelessWidget {
+class OSM extends StatefulWidget {
   final List<Measurement> markerList;
 
   const OSM({
@@ -13,10 +13,17 @@ class OSM extends StatelessWidget {
   }) : super(key: key);
 
   @override
-  Widget build(BuildContext context) {
-    // Init list of polygons
-    List<Polygon> polygons = [];
+  OSMState createState() => OSMState();
+}
+
+class OSMState extends State<OSM> {
+  @override
+  void initState() {
+    super.initState();
+  }
 
+  @override
+  Widget build(BuildContext context) {
     return FlutterMap(
       options: MapOptions(
         bounds: LatLngBounds(
@@ -26,12 +33,9 @@ class OSM extends StatelessWidget {
       ),
       children: [
         TileLayer(
-          urlTemplate: "https://{s}.tile.openstreetmap.org/{z/{x}/{y}.png",
+          urlTemplate: "https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png",
           subdomains: const ['a', 'b', 'c'],
         ),
-        PolygonLayer(
-          polygons: polygons, // Return map with list of polygons included
-        ),
       ],
     );
   }