### 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 
_FORCE_INLINE_ float get_height(float line_separation) const {
			return offset.y + text_buf->get_size().y + text_buf->get_line_count() * line_separation;
		}
	};
	struct Item {
		int index = 0;
		int char_ofs = 0;
		Item *parent = nullptr;
		ItemType type = ITEM_FRAME;
		List<Item *> subitems;
		List<Item *>::Element *E = nullptr;
		int line = 0;
		void _clear_children() {