Fix list schemas

common/sprinklersRpc/schema/list.ts

@@ -65,7 +65,7 @@ export default function list(propSchema: PropSchema): PropSchema {
               propSchema.deserializer(item, itemDone, context, undefined),
           done);
     },
-    beforeDeserialize: () => {},
-    afterDeserialize: () => {},
+    beforeDeserialize: undefined as any,
+    afterDeserialize: undefined as any,
   };
 }