refactor(user-management): add robust error handling to app role changes

This commit enhances the _onUserAppRoleChanged method in the UserManagementBloc by introducing a try-catch block and detailed logging.

This change mirrors the robust implementation of _onUserDashboardRoleChanged, ensuring that any errors during the update process are caught, logged, and handled gracefully, preventing the BLoC's event stream from crashing and improving the overall stability of the user management feature.

Author: fulleni

lib/user_management/bloc/user_management_bloc.dart

@@ -181,10 +181,28 @@ class UserManagementBloc
     UserAppRoleChanged event,
     Emitter<UserManagementState> emit,
   ) async {
-    final userToUpdate = state.users.firstWhere((u) => u.id == event.userId);
-    await _usersRepository.update(
-      id: event.userId,
-      item: userToUpdate.copyWith(appRole: event.appRole),
+    _logger.info(
+      'Attempting to change app role for user: ${event.userId} '
+      'to ${event.appRole.name}',
     );
+    try {
+      final userToUpdate = state.users.firstWhere((u) => u.id == event.userId);
+      _logger.info('Found user in state: $userToUpdate');
+
+      final updatedItem = userToUpdate.copyWith(appRole: event.appRole);
+      _logger.info('Sending updated user object to repository: $updatedItem');
+
+      await _usersRepository.update(
+        id: event.userId,
+        item: updatedItem,
+      );
+    } catch (error, stackTrace) {
+      _logger.severe(
+        'Error changing user app role for ${event.userId}.',
+        error,
+        stackTrace,
+      );
+      addError(error, stackTrace);
+    }
   }
 }