Fix GetAttributeOfType method: add check for empty member info to prevent null reference exceptions

FoodsharingSiegen.Contracts/Helper/AttributeExtensions.cs

@@ -34,6 +34,7 @@ namespace FoodsharingSiegen.Contracts.Helper
         {
             var type = enumVal.GetType();
             var memInfo = type.GetMember(enumVal.ToString());
+            if (memInfo.Length == 0) return null;
             var attributes = memInfo[0].GetCustomAttributes(typeof(T), false);
             return attributes.Length > 0 ? (T)attributes[0] : null;
         }