### 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);
	ItemFrame *item = memnew(ItemFrame);
	item->parent_frame = current_frame;
	_add_item(item, true);
	current_frame = item;
	item->cell = true;
	item->lines.resize(1);
	item->lines[0].from = nullptr;
	item->first_invalid_line.store(0); 
}
int RichTextLabel::get_current_table_column() const {
	ERR_FAIL_COND_V(current->type != ITEM_TABLE, -1);
	ItemTable *table = static_cast<ItemTable *>(current);
	return table->subitems.size() % table->columns.size();
}
void RichTextLabel::pop() {
	_stop_thread();
	MutexLock data_lock(data_mutex);
	ERR_FAIL_NULL(current->parent);
	if (current->type == ITEM_FRAME) {
		current_frame = static_cast<ItemFrame *>(current)->parent_frame;
	}
	current = current->parent;
}
void RichTextLabel::clear() {