add some comments

packages/cubejs-backend-native/src/node_obj_deserializer.rs

@@ -132,15 +132,7 @@ impl<'de, 'a, 'b> Deserializer<'de> for JsValueDeserializer<'a, 'b> {
             visitor.visit_none()
         } else if self.value.is_a::<JsFunction, _>(self.cx) {
             // We can do nothing with the JS functions in native
-            // so let's save them as string for potential usage later
-            // in JS side if needed
-            let value = self
-                .value
-                .downcast::<JsFunction, _>(self.cx)
-                .or_throw(self.cx)?
-                .to_string(self.cx)?
-                .value(self.cx);
-            visitor.visit_string(value)
+            visitor.visit_none()
         } else {
             Err(JsDeserializationError(
                 "Unsupported type for deserialization".to_string(),

rust/cubeorchestrator/src/transport.rs

@@ -82,11 +82,15 @@ pub struct GroupingSet {
     pub sub_id: Option<u32>,
 }
 
+// We can do nothing with JS functions here,
+// but to keep DTOs in sync with reality, let's keep it.
+type JsFunction = String;
+
 #[derive(Debug, Clone, Serialize, Deserialize, Hash, Eq, PartialEq)]
 #[serde(rename_all = "camelCase")]
 pub struct MemberExpression {
-    #[serde(skip_deserializing)]
-    pub expression: Option<Value>,
+    // Made as Option and JsValueDeserializer set's it to None.
+    pub expression: Option<JsFunction>,
     pub cube_name: String,
     pub name: String,
     #[serde(skip_serializing_if = "Option::is_none")]