### 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)

#include <godot_cpp/classes/file_access.hpp>
#include <godot_cpp/classes/os.hpp>
#include <godot_cpp/classes/project_settings.hpp>
#include <godot_cpp/classes/rendering_server.hpp>
#include <godot_cpp/classes/translation_server.hpp>
#include <godot_cpp/core/error_macros.hpp>
using namespace godot;
#define GLOBAL_GET(m_var) ProjectSettings::get_singleton()->get_setting_with_override(m_var)
#else
#include "core/config/project_settings.h"
#include "core/error/error_macros.h"
#include "core/object/worker_thread_pool.h"
#include "core/string/print_string.h"
#include "core/string/translation.h"
#include "modules/modules_enabled.gen.h" 
#endif
#ifdef ICU_STATIC_DATA
#include "icudata.gen.h"
#endif
#ifdef MODULE_MSDFGEN_ENABLED
#include "core/ShapeDistanceFinder.h"
#include "core/contour-combiners.h"
#include "core/edge-selectors.h"
#include "msdfgen.h"
#endif
#ifdef MODULE_SVG_ENABLED
#include "thorvg_svg_in_ot.h"
#endif
hb_font_funcs_t *TextServerAdvanced::funcs = nullptr;
TextServerAdvanced::bmp_font_t *TextServerAdvanced::_bmp_font_create(TextServerAdvanced::FontForSizeAdvanced *p_face, bool p_unref) {