moving jsonValue nil check after extension processing logic

ytypes/container.go

@@ -210,11 +210,6 @@ func unmarshalStruct(schema *yang.Entry, parent interface{}, jsonTree map[string
 			return err
 		}
 
-		if jsonValue == nil {
-			util.DbgPrint("field %s paths %v not present in tree", ft.Name, sp)
-			continue
-		}
-
 		if extensions, hasExtensions := ft.Tag.Lookup("extensions"); hasExtensions {
 			if unmarshalConf.extHandler != nil {
 				jsonValue, err = yext.ProcessExtensions(jsonValue, extensions, unmarshalConf.extHandler)
@@ -224,6 +219,11 @@ func unmarshalStruct(schema *yang.Entry, parent interface{}, jsonTree map[string
 			}
 		}
 
+		if jsonValue == nil {
+			util.DbgPrint("field %s paths %v not present in tree", ft.Name, sp)
+			continue
+		}
+
 		util.DbgPrint("populating field %s type %s with paths %v.", ft.Name, ft.Type, sp)
 		// Only create a new field if it is nil, otherwise update just the
 		// fields that are in the data tree being passed to unmarshal, and