### 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)

int32_t idx = p_data->textures.size() - 1;
		ret = p_data->textures.write[idx].pack_rect(idx, mh, mw);
	}
	return ret;
}
#ifdef MODULE_MSDFGEN_ENABLED
struct MSContext {
	msdfgen::Point2 position;
	msdfgen::Shape *shape = nullptr;
	msdfgen::Contour *contour = nullptr;
};
class DistancePixelConversion {
	double invRange;
public:
	_FORCE_INLINE_ explicit DistancePixelConversion(double range) :
			invRange(1 / range) {}
	_FORCE_INLINE_ void operator()(float *pixels, const msdfgen::MultiAndTrueDistance &distance) const {
		pixels[0] = float(invRange * distance.r + .5);
		pixels[1] = float(invRange * distance.g + .5);
		pixels[2] = float(invRange * distance.b + .5);
		pixels[3] = float(invRange * distance.a + .5);
	}
};
struct MSDFThreadData {
	msdfgen::Bitmap<float, 4> *output;
	msdfgen::Shape *shape;
	msdfgen::Projection *projection;
	DistancePixelConversion *distancePixelConversion;
};
static msdfgen::Point2 ft_point2(const FT_Vector &vector) {