### 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_20", HB_TAG('c', 'v', '2', '0'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_21", HB_TAG('c', 'v', '2', '1'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_22", HB_TAG('c', 'v', '2', '2'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_23", HB_TAG('c', 'v', '2', '3'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_24", HB_TAG('c', 'v', '2', '4'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_25", HB_TAG('c', 'v', '2', '5'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_26", HB_TAG('c', 'v', '2', '6'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_27", HB_TAG('c', 'v', '2', '7'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_28", HB_TAG('c', 'v', '2', '8'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_29", HB_TAG('c', 'v', '2', '9'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_30", HB_TAG('c', 'v', '3', '0'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_31", HB_TAG('c', 'v', '3', '1'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_32", HB_TAG('c', 'v', '3', '2'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_33", HB_TAG('c', 'v', '3', '3'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_34", HB_TAG('c', 'v', '3', '4'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_35", HB_TAG('c', 'v', '3', '5'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_36", HB_TAG('c', 'v', '3', '6'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_37", HB_TAG('c', 'v', '3', '7'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_38", HB_TAG('c', 'v', '3', '8'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_39", HB_TAG('c', 'v', '3', '9'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_40", HB_TAG('c', 'v', '4', '0'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_41", HB_TAG('c', 'v', '4', '1'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_42", HB_TAG('c', 'v', '4', '2'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_43", HB_TAG('c', 'v', '4', '3'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_44", HB_TAG('c', 'v', '4', '4'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_45", HB_TAG('c', 'v', '4', '5'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_46", HB_TAG('c', 'v', '4', '6'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_47", HB_TAG('c', 'v', '4', '7'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_48", HB_TAG('c', 'v', '4', '8'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_49", HB_TAG('c', 'v', '4', '9'), Variant::Type::BOOL, false);