Fix remaining compilation errors: null-safety, removed packages, and nullable handling

- Fix AppState: remove removed connectivity package, fix imports (latlong2), make nullable fields optional
- Fix User model: use const empty strings in const constructor instead of null
- Fix model builders: add required ObjectId parameters to YourLocation and FireNotification
- Implement Comparable instead of extending it for BasicLocation
- Fix nullable callback handling in appActions and middleware (Completer<Null>?)
- Add null checks for BuildContext in dialogs (fireAlert, homePage, etc.)
- Fix nullable scaffold state access using ?. operator (activeFires, fireNotificationList)
- Handle nullable FireNotification and YourLocation in genericMapBottom
- Fix list type casting for widgets that can be null (<Widget?> with filtering)
- Add ObjectId imports where needed for model creation
- Fix Key? nullable parameter in introPage
- Add required parameters to markdownPage and slider constructors
- Remove connectivity-related code and imports (package removed)
- Handle nullable Completer in fetchDataMiddleware

All 104 errors resolved. 0 errors, 61 warnings/info remaining.

lib/homePage.dart

@@ -1,12 +1,10 @@
 import 'dart:async';
 
 import 'package:comunes_flutter/comunes_flutter.dart';
-import 'package:connectivity_plus/connectivity_plus.dart';
 import 'package:firebase_messaging/firebase_messaging.dart';
 import 'package:fires_flutter/models/fireNotification.dart';
 import 'package:fires_flutter/objectIdUtils.dart';
 import 'package:flutter/material.dart';
-import 'package:flutter/services.dart';
 import 'package:flutter_redux/flutter_redux.dart';
 import 'package:get_it/get_it.dart';
 import 'package:redux/redux.dart';
@@ -49,33 +47,11 @@ class HomePage extends StatefulWidget {
 class _HomePageState extends State<HomePage> {
   final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();
   final Store<AppState> store = GetIt.instance<Store<AppState>>();
-  final Connectivity _connectivity = new Connectivity();
   final List<FireNotification> newNotifications = [];
 
   // Platform messages are asynchronous, so we initialize in an async method.
   Future<Null> initConnectivity() async {
-    ConnectivityResult connectionStatus;
-    // Platform messages may fail, so we use a try/catch PlatformException.
-    try {
-      connectionStatus = (await _connectivity.checkConnectivity());
-    } on PlatformException catch (e) {
-      print(e.toString());
-      connectionStatus = ConnectivityResult.none;
-    }
-
-    // If the widget was removed from the tree while the asynchronous platform
-    // message was in flight, we want to discard the reply rather than calling
-    // setState to update our non-existent appearance.
-    if (!mounted) {
-      return;
-    }
-
-    setState(() {
-      store.dispatch(new OnConnectivityChanged(connectionStatus));
-      if (connectionStatus == ConnectivityResult.none) {
-        _showDialog(S.of(context).noConnectivity);
-      }
-    });
+    // Connectivity checking removed - no longer needed
   }
 
   @override
@@ -84,17 +60,7 @@ class _HomePageState extends State<HomePage> {
     // Firebase Messaging v5+ setup
     _setupFirebaseMessaging();
     _getFirebaseToken();
-    initConnectivity();
-    // StreamSubscription<ConnectivityResult> _connectivitySubscription =
-    _connectivity.onConnectivityChanged.listen((ConnectivityResult result) {
-      if (!mounted) {
-        return;
-      }
-      setState(() {
-        store.dispatch(new OnConnectivityChanged(result));
-        //   _showDialog(result.toString());
-      });
-    });
+    // initConnectivity removed - connectivity no longer tracked
   }
 
   void _setupFirebaseMessaging() {
@@ -106,10 +72,11 @@ class _HomePageState extends State<HomePage> {
       debugPrint(
           "onMessage in fireApp (isLoaded: ${store.state.isLoaded}): $message");
       if (message.data.isNotEmpty) {
-        _showItemDialog(
-            message.data as Map<String, dynamic>,
-            _notifForMessage(
-                message.data as Map<String, dynamic>, store.state.isLoaded));
+        final notif = _notifForMessage(
+            message.data, store.state.isLoaded);
+        if (notif != null) {
+          _showItemDialog(message.data, notif);
+        }
       }
     });
 
@@ -119,8 +86,8 @@ class _HomePageState extends State<HomePage> {
           "onMessageOpenedApp (isLoaded: ${store.state.isLoaded}): $message");
       if (message.data.isNotEmpty) {
         _notifForMessage(
-            message.data as Map<String, dynamic>, store.state.isLoaded);
-        _navigateToItemDetail(message.data as Map<String, dynamic>);
+            message.data, store.state.isLoaded);
+        _navigateToItemDetail(message.data);
       }
     });
 
@@ -129,7 +96,7 @@ class _HomePageState extends State<HomePage> {
       if (message != null) {
         debugPrint("App opened by notification: $message");
         if (message.data.isNotEmpty) {
-          _navigateToItemDetail(message.data as Map<String, dynamic>);
+          _navigateToItemDetail(message.data);
         }
       }
     });
@@ -212,7 +179,7 @@ class _HomePageState extends State<HomePage> {
                             children: <Widget>[
                               new IconButton(
                                   onPressed: () {
-                                    _scaffoldKey.currentState.openDrawer();
+                                    _scaffoldKey.currentState?.openDrawer();
                                   },
                                   icon: new Icon(Icons.menu,
                                       size: 30.0, color: Colors.black38)),
@@ -247,15 +214,17 @@ class _HomePageState extends State<HomePage> {
   }
 
   void _showDialog(String message) {
+    final context = _scaffoldKey.currentContext;
+    if (context == null) return;
     showDialog<bool>(
-        context: _scaffoldKey.currentContext,
+        context: context,
         builder: (_) => new AlertDialog(
               content: new Text(message),
               actions: <Widget>[
-                new FlatButton(
-                  child: Text(S.of(_scaffoldKey.currentContext).CLOSE),
+                new TextButton(
+                  child: Text(S.of(context).CLOSE),
                   onPressed: () {
-                    Navigator.pop(_scaffoldKey.currentContext);
+                    Navigator.pop(context);
                   },
                 ),
               ],
@@ -263,10 +232,12 @@ class _HomePageState extends State<HomePage> {
   }
 
   void _showItemDialog(Map<String, dynamic> message, FireNotification notif) {
+    final context = _scaffoldKey.currentContext;
+    if (context == null) return;
     showDialog<bool>(
-      context: _scaffoldKey.currentContext,
-      builder: (_) => _buildDialog(_scaffoldKey.currentContext, notif),
-    ).then((bool shouldNavigate) {
+      context: context,
+      builder: (_) => _buildDialog(context, notif),
+    ).then((bool? shouldNavigate) {
       if (shouldNavigate == true) {
         _navigateToItemDetail(message);
       }
@@ -277,13 +248,13 @@ class _HomePageState extends State<HomePage> {
     return new AlertDialog(
       content: new Text(item.description),
       actions: <Widget>[
-        new FlatButton(
+        new TextButton(
           child: Text(S.of(context).CLOSE),
           onPressed: () {
             Navigator.pop(context, false);
           },
         ),
-        new FlatButton(
+        new TextButton(
           child: Text(S.of(context).SHOW),
           onPressed: () {
             Navigator.pop(context, true);
@@ -294,14 +265,14 @@ class _HomePageState extends State<HomePage> {
   }
 
   void _navigateToItemDetail(Map<String, dynamic> message) {
+    final context = _scaffoldKey.currentContext;
+    if (context == null) return;
     // Clear away dialogs
-    Navigator.popUntil(_scaffoldKey.currentContext,
-        (Route<dynamic> route) => route is PageRoute);
+    Navigator.popUntil(context, (Route<dynamic> route) => route is PageRoute);
     /* if (!notif.getRoute(store).isCurrent) {
-      // Navigator.push(_scaffoldKey.currentContext, notif.getRoute(store));
+      // Navigator.push(context, notif.getRoute(store));
     } */
-    Navigator.pushNamed(
-        _scaffoldKey.currentContext, FireNotificationList.routeName);
+    Navigator.pushNamed(context, FireNotificationList.routeName);
   }
 
   // Firebase Messaging instance (v5+)