### 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)

base_para_direction = UBIDI_LTR;
		} 
		case DIRECTION_RTL: {
			sd->para_direction = DIRECTION_RTL;
			base_para_direction = UBIDI_RTL;
		} 
		case DIRECTION_INHERITED:
		case DIRECTION_AUTO: {
			UBiDiDirection direction = ubidi_getBaseDirection(data, sd->utf16.length());
			if (direction != UBIDI_NEUTRAL) {
				sd->para_direction = (direction == UBIDI_RTL) ? DIRECTION_RTL : DIRECTION_LTR;
				base_para_direction = direction;
			} else {
				sd->para_direction = DIRECTION_LTR;
				base_para_direction = UBIDI_DEFAULT_LTR;
			}
		} 
	}
	if (sd->bidi_override.is_empty()) {
		sd->bidi_override.push_back(Vector3i(sd->start, sd->end, DIRECTION_INHERITED));
	}
	for (int ov = 0; ov < sd->bidi_override.size(); ov++) {
		
		int start = _convert_pos_inv(sd, sd->bidi_override[ov].x - sd->start);
		int end = _convert_pos_inv(sd, sd->bidi_override[ov].y - sd->start);
		if (start < 0 || end - start > sd->utf16.length()) {
			continue;
		}
		UErrorCode err = U_ZERO_ERROR;
		UBiDi *bidi_iter = ubidi_openSized(end - start, 0, &err);