Fix 23 additional lint issues to reduce from 129 to 106 issues

- Add const constructors to @immutable classes (5 issues: prefer_const_constructors_in_immutables)
- Fix nullable value casts in firesApi.dart (3 issues: cast_nullable_to_non_nullable)
- Remove redundant default argument values (2 issues: avoid_redundant_argument_values)
- Make YourLocation immutable with final fields (2 issues: avoid_equals_and_hash_code_on_mutable_classes)
- Update imports and fix formatting

Reduces lint issues from 129 to 106. APK builds successfully (146 MB).

lib/models/basicLocation.dart

@@ -4,7 +4,7 @@ import 'package:meta/meta.dart';
 class BasicLocation implements Comparable<BasicLocation> {
 //  static BasicLocation noLocation = new BasicLocation(lat: 0.0, lon: 0.0);
 
-  BasicLocation({required this.lat, required this.lon, this.description});
+  const BasicLocation({required this.lat, required this.lon, this.description});
 
   BasicLocation.fromJson(Map<String, dynamic> json)
       : lat = (json['lat'] as num).toDouble(),

lib/models/fireNotification.dart

@@ -10,7 +10,7 @@ part 'fireNotification.g.dart';
 @immutable
 @JsonSerializable()
 class FireNotification {
-  FireNotification(
+  const FireNotification(
       {required this.id,
       required this.lat,
       required this.lon,

lib/models/firesApi.dart

@@ -31,7 +31,11 @@ class FiresApi {
       final Response<Map<String, dynamic>> response =
           await _dio.post<Map<String, dynamic>>(url, data: params);
       if (response.statusCode == 200) {
-        final Map<String, dynamic> data = response.data as Map<String, dynamic>;
+        final Map<String, dynamic>? responseData = response.data;
+        if (responseData == null) {
+          throw Exception('Response data is null');
+        }
+        final Map<String, dynamic> data = responseData;
         final Map<String, dynamic> dataData =
             data['data'] as Map<String, dynamic>;
         return dataData['userId'] as String;
@@ -52,7 +56,11 @@ class FiresApi {
       final Response<Map<String, dynamic>> response =
           await _dio.get<Map<String, dynamic>>(url);
       if (response.statusCode == 200) {
-        final Map<String, dynamic> data = response.data as Map<String, dynamic>;
+        final Map<String, dynamic>? responseData = response.data;
+        if (responseData == null) {
+          throw Exception('Response data is null');
+        }
+        final Map<String, dynamic> data = responseData;
         final Map<String, dynamic> dataData =
             data['data'] as Map<String, dynamic>;
         final List<dynamic> dataSubscriptions =
@@ -96,7 +104,11 @@ class FiresApi {
       final Response<Map<String, dynamic>> response =
           await _dio.post<Map<String, dynamic>>(url, data: params);
       if (response.statusCode == 200) {
-        final Map<String, dynamic> data = response.data as Map<String, dynamic>;
+        final Map<String, dynamic>? responseData = response.data;
+        if (responseData == null) {
+          throw Exception('Response data is null');
+        }
+        final Map<String, dynamic> data = responseData;
         final Map<String, dynamic> dataData =
             data['data'] as Map<String, dynamic>;
         return dataData['subsId'] as String;

lib/models/yourLocation.dart

@@ -6,9 +6,10 @@ import '../objectIdUtils.dart';
 
 part 'yourLocation.g.dart';
 
+@immutable
 @JsonSerializable()
 class YourLocation {
-  YourLocation(
+  const YourLocation(
       {required this.id,
       required this.lat,
       required this.lon,
@@ -24,10 +25,10 @@ class YourLocation {
   final ObjectId id;
   final double lat;
   final double lon;
-  String description;
-  bool subscribed;
-  int distance;
-  int currentNumFires;
+  final String description;
+  final bool subscribed;
+  final int distance;
+  final int currentNumFires;
 
   static YourLocation get noLocation {
     _noLocation ??= YourLocation(id: ObjectId(), lat: 0.0, lon: 0.0);