### Godot version

v4.0.beta16.official [518b9e580]

### System information

Windows 10

### Issue description

`RichTextLabel` with `threaded` enabled may crash the game or show the following warning if the node is in another scene:

```
W 0:00:03:0802   test.gd:12 @ load_with_scene(): A Thread object has been re-started without wait_to_finish() having been called on it. Please do so to ensure correct cleanup of the thread.
  <C++ Source>   core/os/thread.cpp:76 @ start()
  <Stack Trace>  test.gd:12 @ load_with_scene()
                 test.gd:6 @ load_items()
                 test.gd:26 @ _on_button_pressed()
```

It may crash the game (without any warning) if it's added directly.

In `v4.0.beta15.official [4fa6edc88]` I was able to reproduce the same warning on my project but I can't reproduce it in the attached MRP. I get a different error and will crash too if the node is added directly:

```
E 0:00:03:0019   remove_from_group: Condition "!E" is true.
  <C++ Source>   scene/main/scene_tree.cpp:157 @ remove_from_group()
```


### Steps to reproduce

Click on the  `Load with scene` or `Load with node` buttons in the attached MRP until it shows a warning/error or crashes. It may take a while.

### Minimal reproduction project

[add_chid_bug_b16.zip](https://github.com/godotengine/godot/files/10521402/add_chid_bug_b16.zip)

ClassDB::bind_method(D_METHOD("set_tab_size", "spaces"), &RichTextLabel::set_tab_size);
	ClassDB::bind_method(D_METHOD("get_tab_size"), &RichTextLabel::get_tab_size);
	ClassDB::bind_method(D_METHOD("set_fit_content", "enabled"), &RichTextLabel::set_fit_content);
	ClassDB::bind_method(D_METHOD("is_fit_content_enabled"), &RichTextLabel::is_fit_content_enabled);
	ClassDB::bind_method(D_METHOD("set_selection_enabled", "enabled"), &RichTextLabel::set_selection_enabled);
	ClassDB::bind_method(D_METHOD("is_selection_enabled"), &RichTextLabel::is_selection_enabled);
	ClassDB::bind_method(D_METHOD("set_context_menu_enabled", "enabled"), &RichTextLabel::set_context_menu_enabled);
	ClassDB::bind_method(D_METHOD("is_context_menu_enabled"), &RichTextLabel::is_context_menu_enabled);
	ClassDB::bind_method(D_METHOD("set_shortcut_keys_enabled", "enabled"), &RichTextLabel::set_shortcut_keys_enabled);
	ClassDB::bind_method(D_METHOD("is_shortcut_keys_enabled"), &RichTextLabel::is_shortcut_keys_enabled);
	ClassDB::bind_method(D_METHOD("set_deselect_on_focus_loss_enabled", "enable"), &RichTextLabel::set_deselect_on_focus_loss_enabled);
	ClassDB::bind_method(D_METHOD("is_deselect_on_focus_loss_enabled"), &RichTextLabel::is_deselect_on_focus_loss_enabled);
	ClassDB::bind_method(D_METHOD("get_selection_from"), &RichTextLabel::get_selection_from);
	ClassDB::bind_method(D_METHOD("get_selection_to"), &RichTextLabel::get_selection_to);
	ClassDB::bind_method(D_METHOD("select_all"), &RichTextLabel::select_all);
	ClassDB::bind_method(D_METHOD("get_selected_text"), &RichTextLabel::get_selected_text);
	ClassDB::bind_method(D_METHOD("deselect"), &RichTextLabel::deselect);
	ClassDB::bind_method(D_METHOD("parse_bbcode", "bbcode"), &RichTextLabel::parse_bbcode);
	ClassDB::bind_method(D_METHOD("append_text", "bbcode"), &RichTextLabel::append_text);
	ClassDB::bind_method(D_METHOD("get_text"), &RichTextLabel::get_text);
	ClassDB::bind_method(D_METHOD("is_ready"), &RichTextLabel::is_ready);
	ClassDB::bind_method(D_METHOD("set_threaded", "threaded"), &RichTextLabel::set_threaded);
	ClassDB::bind_method(D_METHOD("is_threaded"), &RichTextLabel::is_threaded);
	ClassDB::bind_method(D_METHOD("set_progress_bar_delay", "delay_ms"), &RichTextLabel::set_progress_bar_delay);
	ClassDB::bind_method(D_METHOD("get_progress_bar_delay"), &RichTextLabel::get_progress_bar_delay);
	ClassDB::bind_method(D_METHOD("set_visible_characters", "amount"), &RichTextLabel::set_visible_characters);
	ClassDB::bind_method(D_METHOD("get_visible_characters"), &RichTextLabel::get_visible_characters);
	ClassDB::bind_method(D_METHOD("get_visible_characters_behavior"), &RichTextLabel::get_visible_characters_behavior);
	ClassDB::bind_method(D_METHOD("set_visible_characters_behavior", "behavior"), &RichTextLabel::set_visible_characters_behavior);
	ClassDB::bind_method(D_METHOD("set_visible_ratio", "ratio"), &RichTextLabel::set_visible_ratio);