fixed some potential crashes in datatype lookups and a keyalreadyexists exception in datatype lookup

umbraco.MacroEngines.Juno/RazorDynamicNode/DynamicNode.cs

@@ -396,7 +396,10 @@ namespace umbraco.MacroEngines
                     //special casing for true/false properties
                     //int/decimal are handled by ConvertPropertyValueByDataType
                     //fallback is stringT
-
+                    if (n.NodeTypeAlias == null && data.Alias == null)
+                    {
+                        throw new ArgumentNullException("No node alias or property alias available. Unable to look up the datatype of the property you are trying to fetch.");
+                    }
                     Guid dataType = ContentType.GetDataType(n.NodeTypeAlias, data.Alias);
 
                     if (RazorDataTypeModelTypes == null)

umbraco/cms/businesslogic/ContentType.cs

@@ -193,12 +193,17 @@ namespace umbraco.cms.businesslogic
             }
             finally
             {
-                reader.Close();
+                if (reader != null)
+                {
+                    reader.Close();
+                }
             }
 
             //add to cache
-            _propertyTypeCache.Add(key, controlId);
-
+            if (!_propertyTypeCache.ContainsKey(key))
+            {
+                _propertyTypeCache.Add(key, controlId);
+            }
             return controlId;
 
         }