message: fix visualization debug scene
  Fixes
  Found a fix during triage, as I tried to reproduce the issue. For some reason the visualization UI component was never attached to the scene, and its size was never set. Adding that fixed the issue immediately.
  <img width="287" alt="image" src="https://user-images.githubusercontent.com/919491/217581444-4d6463cd-ff7f-4292-9355-edee15221e40.png">
diff: @@ -119,6 +119,7 @@ fn init(app: &Application) {
  .expect("Couldn't find Graph class.");
  let visualization = vis_class.new_instance(app).expect("Couldn't create visualiser.");
  visualization.activate.emit(());
  + scene.add_child(&visualization);
  let network = enso_frp::Network::new("VisualizationExample");
  enso_frp::extend! { network
  @@ -137,7 +138,6 @@ fn init(app: &Application) {
  let data = generate_data(
  (time_info.since_animation_loop_started.unchecked_raw() / 1000.0).into(),
  );
  - let data = Rc::new(data);
  let content = serde_json::to_value(data).unwrap();
  let data = Data::from(content);
  @@ -146,6 +146,7 @@ fn init(app: &Application) {
  // Temporary code removing the web-loader instance.
  // To be changed in the future.
  if was_rendered && !loader_hidden {
  + visualization.set_size.emit(Vector2(300.0, 300.0));
  web::document
  .get_element_by_id("loader")
  .map(|t| t.parent_node().map(|p| p.remove_child(&t).unwrap()));
  