fix: handle alarm/query null-safety issues

lib/app/data/providers/google_cloud_api_provider.dart

@@ -89,7 +89,9 @@ class GoogleCloudProvider {
       await _firebaseAuthInstance.signOut();
       await getInstance();
     }
-    final authHeaders = await _googleSignIn.currentUser!.authHeaders;
+    final currentUser = _googleSignIn.currentUser;
+    if (currentUser == null) return null;
+    final authHeaders = await currentUser.authHeaders;
     final httpClient = GoogleHttpClient(authHeaders);
     var dataList = await CalendarApi(httpClient).calendarList.list();
 
@@ -101,8 +103,12 @@ class GoogleCloudProvider {
   }
 
   static Future<List<Event>?> getEvents(String calenderId) async {
-    await getInstance();
-    final authHeaders = await _googleSignIn.currentUser!.authHeaders;
+    if (_googleSignIn.currentUser == null) {
+      await getInstance();
+    }
+    final currentUser = _googleSignIn.currentUser;
+    if (currentUser == null) return null;
+    final authHeaders = await currentUser.authHeaders;
     final httpClient = GoogleHttpClient(authHeaders);
     var dataList = await CalendarApi(httpClient).events.list(calenderId);
     if (dataList.items != null) {

lib/app/data/providers/isar_provider.dart

@@ -331,6 +331,9 @@ class IsarDb {
         .and()
         .alarmTimeEqualTo(time)
         .findAll();
+    if (alarms.isEmpty) {
+      throw StateError('No enabled alarm found for time: $time');
+    }
     return alarms.first;
   }
 

lib/app/modules/addOrUpdateAlarm/views/ringtone_selection_page.dart

@@ -160,6 +160,23 @@ class RingtoneSelectionPage extends GetView<AddOrUpdateAlarmController> {
   }
 
   Widget _buildSystemRingtonesTab() {
+    if (GetPlatform.isIOS) {
+      return Center(
+        child: Padding(
+          padding: const EdgeInsets.all(32.0),
+          child: Text(
+            'System ringtones are currently only supported on Android.\n\nPlease upload a custom ringtone to use this feature.',
+            textAlign: TextAlign.center,
+            style: TextStyle(
+              color: themeController.primaryTextColor.value.withOpacity(0.7),
+              fontSize: 16,
+              height: 1.5,
+            ),
+          ),
+        ),
+      );
+    }
+
     return SystemRingtonePicker(
       isFullScreen: true,
     );

lib/app/modules/notifications/controllers/notifications_controller.dart

@@ -8,8 +8,6 @@ import '../../../data/providers/firestore_provider.dart';
 import '../../home/controllers/home_controller.dart';
 
 class NotificationsController extends GetxController {
-  //TODO: Implement NotificationsController
-
   late List notifications = [].obs;
   HomeController homeController = Get.find<HomeController>();
   late List allProfiles = [].obs;