### 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("contextual_alternates", HB_TAG('c', 'a', 'l', 't'), Variant::Type::BOOL, false);
	_insert_feature("case_sensitive_forms", HB_TAG('c', 'a', 's', 'e'), Variant::Type::BOOL, false);
	_insert_feature("glyph_composition", HB_TAG('c', 'c', 'm', 'p'), Variant::Type::INT, true);
	_insert_feature("conjunct_form_after_ro", HB_TAG('c', 'f', 'a', 'r'), Variant::Type::INT, true);
	_insert_feature("contextual_half_width_spacing", HB_TAG('c', 'h', 'w', 's'), Variant::Type::INT, true);
	_insert_feature("conjunct_forms", HB_TAG('c', 'j', 'c', 't'), Variant::Type::INT, true);
	_insert_feature("contextual_ligatures", HB_TAG('c', 'l', 'i', 'g'), Variant::Type::BOOL, false);
	_insert_feature("centered_cjk_punctuation", HB_TAG('c', 'p', 'c', 't'), Variant::Type::BOOL, false);
	_insert_feature("capital_spacing", HB_TAG('c', 'p', 's', 'p'), Variant::Type::BOOL, false);
	_insert_feature("contextual_swash", HB_TAG('c', 's', 'w', 'h'), Variant::Type::INT, false);
	_insert_feature("cursive_positioning", HB_TAG('c', 'u', 'r', 's'), Variant::Type::INT, true);
	_insert_feature("character_variant_01", HB_TAG('c', 'v', '0', '1'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_02", HB_TAG('c', 'v', '0', '2'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_03", HB_TAG('c', 'v', '0', '3'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_04", HB_TAG('c', 'v', '0', '4'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_05", HB_TAG('c', 'v', '0', '5'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_06", HB_TAG('c', 'v', '0', '6'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_07", HB_TAG('c', 'v', '0', '7'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_08", HB_TAG('c', 'v', '0', '8'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_09", HB_TAG('c', 'v', '0', '9'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_10", HB_TAG('c', 'v', '1', '0'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_11", HB_TAG('c', 'v', '1', '1'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_12", HB_TAG('c', 'v', '1', '2'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_13", HB_TAG('c', 'v', '1', '3'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_14", HB_TAG('c', 'v', '1', '4'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_15", HB_TAG('c', 'v', '1', '5'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_16", HB_TAG('c', 'v', '1', '6'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_17", HB_TAG('c', 'v', '1', '7'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_18", HB_TAG('c', 'v', '1', '8'), Variant::Type::BOOL, false);
	_insert_feature("character_variant_19", HB_TAG('c', 'v', '1', '9'), Variant::Type::BOOL, false);