Implemented loading indicator for mapview

lib/pages/map_page.dart

@@ -22,14 +22,28 @@ class MapPage extends StatefulWidget {
 class _MapPageState extends State<MapPage> {
   final _mapController = MapController();
   late FloodStationProvider _floodStationProvider;
+  bool _loading = false;
 
   @override
   Widget build(BuildContext context) {
     _floodStationProvider = context.watch<FloodStationProvider>();
-    if (_floodStationProvider.allStations.isEmpty) {
+    if (_loading == true) {
+      return Center(
+        child: CircularProgressIndicator(),
+      );
+    } else if (_floodStationProvider.allStations.isEmpty) {
       return Center(
         child: ElevatedButton(
-          onPressed: _floodStationProvider.loadAllStations,
+          onPressed: () {
+            setState(() {
+              _loading = true;
+            });
+            _floodStationProvider
+                .loadAllStations()
+                .whenComplete(() => setState(() {
+                      _loading = false;
+                    }));
+          },
           child: Text('Load Map'),
         ),
       );