More defensive partition calculation.

backend/src/Squidex.Domain.Apps.Core.Model/Rules/EnrichedEvents/EnrichedCommentEvent.cs

@@ -25,7 +25,7 @@ namespace Squidex.Domain.Apps.Core.Rules.EnrichedEvents
         [IgnoreDataMember]
         public override long Partition
         {
-            get => MentionedUser.Id.GetHashCode();
+            get => MentionedUser?.Id.GetHashCode() ?? 0;
         }
 
         public bool ShouldSerializeMentionedUser()

backend/src/Squidex.Domain.Apps.Core.Model/Rules/EnrichedEvents/EnrichedSchemaEvent.cs

@@ -20,7 +20,7 @@ namespace Squidex.Domain.Apps.Core.Rules.EnrichedEvents
 
         public override long Partition
         {
-            get => SchemaId.GetHashCode();
+            get => SchemaId?.GetHashCode() ?? 0;
         }
     }
 }

backend/src/Squidex.Domain.Apps.Core.Model/Rules/EnrichedEvents/EnrichedUsageExceededEvent.cs

@@ -15,7 +15,7 @@ namespace Squidex.Domain.Apps.Core.Rules.EnrichedEvents
 
         public override long Partition
         {
-            get => AppId.GetHashCode();
+            get => AppId?.GetHashCode() ?? 0;
         }
     }
 }