### 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)

ERR_FAIL_COND_V_MSG(U_FAILURE(err), false, u_errorName(err));
		switch (static_cast<TextServer::Direction>(sd->bidi_override[ov].z)) {
			case DIRECTION_LTR: {
				ubidi_setPara(bidi_iter, data + start, end - start, UBIDI_LTR, nullptr, &err);
			} 
			case DIRECTION_RTL: {
				ubidi_setPara(bidi_iter, data + start, end - start, UBIDI_RTL, nullptr, &err);
			} 
			case DIRECTION_INHERITED: {
				ubidi_setPara(bidi_iter, data + start, end - start, base_para_direction, nullptr, &err);
			} 
			case DIRECTION_AUTO: {
				UBiDiDirection direction = ubidi_getBaseDirection(data + start, end - start);
				if (direction != UBIDI_NEUTRAL) {
					ubidi_setPara(bidi_iter, data + start, end - start, direction, nullptr, &err);
				} else {
					ubidi_setPara(bidi_iter, data + start, end - start, base_para_direction, nullptr, &err);
				}
			} 
		}
		ERR_FAIL_COND_V_MSG(U_FAILURE(err), false, u_errorName(err));
		sd->bidi_iter.push_back(bidi_iter);
		err = U_ZERO_ERROR;
		int bidi_run_count = ubidi_countRuns(bidi_iter, &err);
		ERR_FAIL_COND_V_MSG(U_FAILURE(err), false, u_errorName(err));
		for (int i = 0; i < bidi_run_count; i++) {
			int32_t _bidi_run_start = 0;
			int32_t _bidi_run_length = 0;
			hb_direction_t bidi_run_direction = HB_DIRECTION_INVALID;
			bool is_rtl = (ubidi_getVisualRun(bidi_iter, i, &_bidi_run_start, &_bidi_run_length) == UBIDI_LTR);