use _eventRegistrationRepository.CountAsync instead.

src/EventHub.Application/Events/Registrations/EventRegistrationAppService.cs

@@ -83,11 +83,7 @@ namespace EventHub.Events.Registrations
 
         public async Task<int> GetAttendeeCountAsync(Guid eventId)
         {
-            var eventRegistrationQueryable = await _eventRegistrationRepository.GetQueryableAsync();
-
-            var query = eventRegistrationQueryable.Where(x => x.EventId == eventId);
-
-            return await AsyncExecuter.CountAsync(query);
+            return await _eventRegistrationRepository.CountAsync(x => x.EventId == eventId);
         }
     }
 }

src/EventHub.Application/Organizations/OrganizationAppService.cs

@@ -102,6 +102,7 @@ namespace EventHub.Organizations
 
             if (organization.OwnerUserId != CurrentUser.GetId())
             {
+                //TODO: throw AbpAuthorizationException instead 
                 throw new BusinessException(EventHubErrorCodes.NotAuthorizedToUpdateOrganizationProfile)
                     .WithData("OrganizationName", organization.DisplayName);
             }
@@ -125,6 +126,7 @@ namespace EventHub.Organizations
             
             if (organization.OwnerUserId != CurrentUser.GetId())
             {
+                //TODO: throw AbpAuthorizationException instead
                 throw new BusinessException(EventHubErrorCodes.NotAuthorizedToUpdateOrganizationProfile)
                     .WithData("Name", organization.DisplayName);
             }