### 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 (!is_visible()) {
		return 0;
	}
	const_cast<RichTextLabel *>(this)->_validate_line_caches();
	return visible_line_count;
}
void RichTextLabel::set_selection_enabled(bool p_enabled) {
	if (selection.enabled == p_enabled) {
		return;
	}
	selection.enabled = p_enabled;
	if (!p_enabled) {
		if (selection.active) {
			deselect();
		}
		set_focus_mode(FOCUS_NONE);
	} else {
		set_focus_mode(FOCUS_ALL);
	}
}
void RichTextLabel::set_deselect_on_focus_loss_enabled(const bool p_enabled) {
	if (deselect_on_focus_loss_enabled == p_enabled) {
		return;
	}
	deselect_on_focus_loss_enabled = p_enabled;
	if (p_enabled && selection.active && !has_focus()) {
		deselect();
	}
}
Variant RichTextLabel::get_drag_data(const Point2 &p_point) {