### Godot version

master ([06ccbfe](https://github.com/godotengine/godot/commit/06ccbfe8eec6e840db3df2360dc2804386f940b8))

### System information

PopOS 22.04

### Issue description

Sometimes the doc page is broken when the engine is closed and then restarted.
Closing the doc and opening it again fixes it.

![2023-05-27_22-15](https://github.com/godotengine/godot/assets/3624853/ed202a55-03e8-420a-bc1c-ccfc7f7cd02a)


### Steps to reproduce

- Open a documentation page for any node
- Restart Godot

### Minimal reproduction project

NA

EDIT : Added the commit hash @Calinou 
_stop_thread();
	MutexLock data_lock(data_mutex);
	ERR_FAIL_COND(current->type == ITEM_TABLE);
	ERR_FAIL_COND(p_level < 0);
	ItemList *item = memnew(ItemList);
	item->list_type = p_list;
	item->level = p_level;
	item->capitalize = p_capitalize;
	item->bullet = p_bullet;
	_add_item(item, true, true);
}
void RichTextLabel::push_meta(const Variant &p_meta) {
	_stop_thread();
	MutexLock data_lock(data_mutex);
	ERR_FAIL_COND(current->type == ITEM_TABLE);
	ItemMeta *item = memnew(ItemMeta);
	item->meta = p_meta;
	_add_item(item, true);
}
void RichTextLabel::push_hint(const String &p_string) {
	_stop_thread();
	MutexLock data_lock(data_mutex);
	ERR_FAIL_COND(current->type == ITEM_TABLE);
	ItemHint *item = memnew(ItemHint);
	item->description = p_string;
	_add_item(item, true);
}
void RichTextLabel::push_table(int p_columns, InlineAlignment p_alignment, int p_align_to_row) {