### 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)

_THREAD_SAFE_METHOD_
	const ShapedTextDataAdvanced *sd = shaped_owner.get_or_null(p_shaped);
	ERR_FAIL_COND_V(!sd, String());
	return sd->custom_punct;
}
void TextServerAdvanced::_shaped_text_set_bidi_override(const RID &p_shaped, const Array &p_override) {
	ShapedTextDataAdvanced *sd = shaped_owner.get_or_null(p_shaped);
	ERR_FAIL_COND(!sd);
	MutexLock lock(sd->mutex);
	if (sd->parent != RID()) {
		full_copy(sd);
	}
	sd->bidi_override.clear();
	for (int i = 0; i < p_override.size(); i++) {
		if (p_override[i].get_type() == Variant::VECTOR3I) {
			const Vector3i &r = p_override[i];
			sd->bidi_override.push_back(r);
		} else if (p_override[i].get_type() == Variant::VECTOR2I) {
			const Vector2i &r = p_override[i];
			sd->bidi_override.push_back(Vector3i(r.x, r.y, DIRECTION_INHERITED));
		}
	}
	invalidate(sd, false);
}
void TextServerAdvanced::_shaped_text_set_orientation(const RID &p_shaped, TextServer::Orientation p_orientation) {