### 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 
if (r_frame != nullptr) {
		*r_frame = nullptr;
	}
	if (r_line != nullptr) {
		*r_line = 0;
	}
	Item *item = p_item;
	while (item) {
		if (item->parent != nullptr && item->parent->type == ITEM_FRAME) {
			if (r_frame != nullptr) {
				*r_frame = static_cast<ItemFrame *>(item->parent);
			}
			if (r_line != nullptr) {
				*r_line = item->line;
			}
			return;
		}
		item = item->parent;
	}
}
RichTextLabel::Item *RichTextLabel::_find_indentable(Item *p_item) {