### 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)

_insert_feature("character_variant_80", HB_TAG('c', 'v', '8', '0'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_81", HB_TAG('c', 'v', '8', '1'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_82", HB_TAG('c', 'v', '8', '2'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_83", HB_TAG('c', 'v', '8', '3'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_84", HB_TAG('c', 'v', '8', '4'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_85", HB_TAG('c', 'v', '8', '5'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_86", HB_TAG('c', 'v', '8', '6'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_87", HB_TAG('c', 'v', '8', '7'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_88", HB_TAG('c', 'v', '8', '8'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_89", HB_TAG('c', 'v', '8', '9'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_90", HB_TAG('c', 'v', '9', '0'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_91", HB_TAG('c', 'v', '9', '1'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_92", HB_TAG('c', 'v', '9', '2'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_93", HB_TAG('c', 'v', '9', '3'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_94", HB_TAG('c', 'v', '9', '4'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_95", HB_TAG('c', 'v', '9', '5'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_96", HB_TAG('c', 'v', '9', '6'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_97", HB_TAG('c', 'v', '9', '7'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_98", HB_TAG('c', 'v', '9', '8'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_99", HB_TAG('c', 'v', '9', '9'), Variant::Type::BOOL, false);
	_insert_feature("petite_capitals_from_capitals", HB_TAG('c', '2', 'p', 'c'), Variant::Type::BOOL, false);
	_insert_feature("small_capitals_from_capitals", HB_TAG('c', '2', 's', 'c'), Variant::Type::BOOL, false);
	_insert_feature("distances", HB_TAG('d', 'i', 's', 't'), Variant::Type::INT, true);
	_insert_feature("discretionary_ligatures", HB_TAG('d', 'l', 'i', 'g'), Variant::Type::BOOL, false);
	_insert_feature("denominators", HB_TAG('d', 'n', 'o', 'm'), Variant::Type::BOOL, false);
	_insert_feature("dotless_forms", HB_TAG('d', 't', 'l', 's'), Variant::Type::INT, true);
	_insert_feature("expert_forms", HB_TAG('e', 'x', 'p', 't'), Variant::Type::BOOL, true);
	_insert_feature("final_glyph_on_line_alternates", HB_TAG('f', 'a', 'l', 't'), Variant::Type::INT, false);
	_insert_feature("terminal_forms_2", HB_TAG('f', 'i', 'n', '2'), Variant::Type::INT, true);
	_insert_feature("terminal_forms_3", HB_TAG('f', 'i', 'n', '3'), Variant::Type::INT, true);