Removed unnecessary Assume()

There were a number of unnecessary `Assume()` checks. These are necessary when checking fields that could be `null`. Since the database columns these are checking are not nullable, however, this condition should never happen. And, if it does, the `SqlDataReader` extension methods will likely throw an exception before these `Assume()` methods are ever called, since most of the `SqlDataReader` extensions are (by design) not aware of `DBNull`.

Author: JeremyCaney

OnTopic.Data.Sql/SqlTopicRepository.cs

@@ -109,16 +109,10 @@ private static void SetIndexedAttributes(SqlDataReader reader, Dictionary<int, T
         version                 = reader.GetVersion();
       }
 
-      /*------------------------------------------------------------------------------------------------------------------------
-      | Validate conditions
-      \-----------------------------------------------------------------------------------------------------------------------*/
-      Contract.Assume(id, $"The 'TopicID' field is missing from the topic. This is an unexpected condition.");
-      Contract.Assume(name, $"The 'AttributeKey' field is missing from the topic. This is an unexpected condition.");
-
       /*------------------------------------------------------------------------------------------------------------------------
       | Handle empty attributes (treat empty as null)
       \-----------------------------------------------------------------------------------------------------------------------*/
-      if (String.IsNullOrEmpty(value) || DBNull.Value.Equals(value)) return;
+      if (String.IsNullOrEmpty(attributeValue)) return;
 
       /*------------------------------------------------------------------------------------------------------------------------
       | Identify topic
@@ -158,11 +152,6 @@ private static void SetExtendedAttributes(SqlDataReader reader, Dictionary<int,
         version                 = reader.GetVersion();
       }
 
-      /*------------------------------------------------------------------------------------------------------------------------
-      | Validate conditions
-      \-----------------------------------------------------------------------------------------------------------------------*/
-      Contract.Assume(id, $"The 'TopicID' field is missing from the topic. This is an unexpected condition.");
-
       /*------------------------------------------------------------------------------------------------------------------------
       | Load SQL XML into XmlDocument
       \-----------------------------------------------------------------------------------------------------------------------*/