### 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)

if ((sd_glyphs[j].start >= bidi_run_start) && (sd_glyphs[j].end <= bidi_run_end)) {
						
						Glyph gl = sd_glyphs[j];
						Variant key;
						bool find_embedded = false;
						if (gl.count == 1) {
							for (const KeyValue<Variant, ShapedTextDataAdvanced::EmbeddedObject> &E : p_sd->objects) {
								if (E.value.pos == gl.start) {
									find_embedded = true;
									key = E.key;
									p_new_sd->objects[key] = E.value;
									
								}
							}
						}
						if (find_embedded) {
							if (p_new_sd->orientation == ORIENTATION_HORIZONTAL) {
								p_new_sd->objects[key].rect.position.x = p_new_sd->width;
								p_new_sd->width += p_new_sd->objects[key].rect.size.x;
							} else {
								p_new_sd->objects[key].rect.position.y = p_new_sd->width;
								p_new_sd->width += p_new_sd->objects[key].rect.size.y;
							}
						} else {
							if (gl.font_rid.is_valid()) {
								if (p_new_sd->orientation == ORIENTATION_HORIZONTAL) {
									p_new_sd->ascent = MAX(p_new_sd->ascent, MAX(_font_get_ascent(gl.font_rid, gl.font_size), -gl.y_off));
									p_new_sd->descent = MAX(p_new_sd->descent, MAX(_font_get_descent(gl.font_rid, gl.font_size), gl.y_off));
								} else {
									p_new_sd->ascent = MAX(p_new_sd->ascent, Math::round(_font_get_glyph_advance(gl.font_rid, gl.font_size, gl.index).x * 0.5));