### 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)

E.value.rect.position.y -= E.value.baseline;
					} 
					case INLINE_ALIGNMENT_TOP_TO: {
						
					} 
				}
				full_ascent = MAX(full_ascent, -E.value.rect.position.y);
				full_descent = MAX(full_descent, E.value.rect.position.y + E.value.rect.size.y);
			} else {
				switch (E.value.inline_align & INLINE_ALIGNMENT_TEXT_MASK) {
					case INLINE_ALIGNMENT_TO_TOP: {
						E.value.rect.position.x = -p_sd->ascent;
					} 
					case INLINE_ALIGNMENT_TO_CENTER: {
						E.value.rect.position.x = (-p_sd->ascent + p_sd->descent) / 2;
					} 
					case INLINE_ALIGNMENT_TO_BASELINE: {
						E.value.rect.position.x = 0;
					} 
					case INLINE_ALIGNMENT_TO_BOTTOM: {
						E.value.rect.position.x = p_sd->descent;
					} 
				}
				switch (E.value.inline_align & INLINE_ALIGNMENT_IMAGE_MASK) {
					case INLINE_ALIGNMENT_BOTTOM_TO: {
						E.value.rect.position.x -= E.value.rect.size.x;
					} 
					case INLINE_ALIGNMENT_CENTER_TO: {
						E.value.rect.position.x -= E.value.rect.size.x / 2;
					}