### 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)

MSContext *context = static_cast<MSContext *>(user);
	context->contour->addEdge(new msdfgen::QuadraticSegment(context->position, ft_point2(*control), ft_point2(*to)));
	context->position = ft_point2(*to);
	return 0;
}
static int ft_cubic_to(const FT_Vector *control1, const FT_Vector *control2, const FT_Vector *to, void *user) {
	MSContext *context = static_cast<MSContext *>(user);
	context->contour->addEdge(new msdfgen::CubicSegment(context->position, ft_point2(*control1), ft_point2(*control2), ft_point2(*to)));
	context->position = ft_point2(*to);
	return 0;
}
void TextServerAdvanced::_generateMTSDF_threaded(void *p_td, uint32_t p_y) {
	MSDFThreadData *td = static_cast<MSDFThreadData *>(p_td);
	msdfgen::ShapeDistanceFinder<msdfgen::OverlappingContourCombiner<msdfgen::MultiAndTrueDistanceSelector>> distanceFinder(*td->shape);
	int row = td->shape->inverseYAxis ? td->output->height() - p_y - 1 : p_y;
	for (int col = 0; col < td->output->width(); ++col) {
		int x = (p_y % 2) ? td->output->width() - col - 1 : col;
		msdfgen::Point2 p = td->projection->unproject(msdfgen::Point2(x + .5, p_y + .5));
		msdfgen::MultiAndTrueDistance distance = distanceFinder.distance(p);
		td->distancePixelConversion->operator()(td->output->operator()(x, row), distance);
	}
}
_FORCE_INLINE_ TextServerAdvanced::FontGlyph TextServerAdvanced::rasterize_msdf(FontAdvanced *p_font_data, FontForSizeAdvanced *p_data, int p_pixel_range, int p_rect_margin, FT_Outline *outline, const Vector2 &advance) const {