### 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_50", HB_TAG('c', 'v', '5', '0'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_51", HB_TAG('c', 'v', '5', '1'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_52", HB_TAG('c', 'v', '5', '2'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_53", HB_TAG('c', 'v', '5', '3'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_54", HB_TAG('c', 'v', '5', '4'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_55", HB_TAG('c', 'v', '5', '5'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_56", HB_TAG('c', 'v', '5', '6'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_57", HB_TAG('c', 'v', '5', '7'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_58", HB_TAG('c', 'v', '5', '8'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_59", HB_TAG('c', 'v', '5', '9'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_60", HB_TAG('c', 'v', '6', '0'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_61", HB_TAG('c', 'v', '6', '1'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_62", HB_TAG('c', 'v', '6', '2'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_63", HB_TAG('c', 'v', '6', '3'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_64", HB_TAG('c', 'v', '6', '4'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_65", HB_TAG('c', 'v', '6', '5'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_66", HB_TAG('c', 'v', '6', '6'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_67", HB_TAG('c', 'v', '6', '7'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_68", HB_TAG('c', 'v', '6', '8'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_69", HB_TAG('c', 'v', '6', '9'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_70", HB_TAG('c', 'v', '7', '0'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_71", HB_TAG('c', 'v', '7', '1'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_72", HB_TAG('c', 'v', '7', '2'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_73", HB_TAG('c', 'v', '7', '3'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_74", HB_TAG('c', 'v', '7', '4'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_75", HB_TAG('c', 'v', '7', '5'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_76", HB_TAG('c', 'v', '7', '6'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_77", HB_TAG('c', 'v', '7', '7'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_78", HB_TAG('c', 'v', '7', '8'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_79", HB_TAG('c', 'v', '7', '9'), Variant::Type::BOOL, false);