### 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)

RichTextLabel *rtl = reinterpret_cast<RichTextLabel *>(self);
	rtl->set_physics_process_internal(true);
	rtl->_process_line_caches();
	rtl->set_physics_process_internal(false);
	rtl->updating.store(false);
	rtl->call_deferred(SNAME("queue_redraw"));
}
void RichTextLabel::_stop_thread() {
	if (threaded) {
		stop_thread.store(true);
		thread.wait_to_finish();
	}
}
bool RichTextLabel::is_ready() const {
	if (updating.load()) {
		return false;
	}
	return (main->first_invalid_line.load() == (int)main->lines.size() && main->first_resized_line.load() == (int)main->lines.size() && main->first_invalid_font_line.load() == (int)main->lines.size());
}
void RichTextLabel::set_threaded(bool p_threaded) {
	if (threaded != p_threaded) {
		_stop_thread();
		threaded = p_threaded;
		queue_redraw();
	}
}
bool RichTextLabel::is_threaded() const {