### 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 
theme_cache.table_h_separation = get_theme_constant(SNAME("table_h_separation"));
	theme_cache.table_v_separation = get_theme_constant(SNAME("table_v_separation"));
	theme_cache.table_odd_row_bg = get_theme_color(SNAME("table_odd_row_bg"));
	theme_cache.table_even_row_bg = get_theme_color(SNAME("table_even_row_bg"));
	theme_cache.table_border = get_theme_color(SNAME("table_border"));
	theme_cache.base_scale = get_theme_default_base_scale();
}
void RichTextLabel::_notification(int p_what) {
	switch (p_what) {
		case NOTIFICATION_MOUSE_EXIT: {
			if (meta_hovering) {
				meta_hovering = nullptr;
				emit_signal(SNAME("meta_hover_ended"), current_meta);
				current_meta = false;
				queue_redraw();
			}
		} break;
		case NOTIFICATION_RESIZED: {
			_stop_thread();
			main->first_resized_line.store(0); 
			queue_redraw();
		} break;
		case NOTIFICATION_THEME_CHANGED: {
			_stop_thread();
			main->first_invalid_font_line.store(0); 
			queue_redraw();
		} break;
		case NOTIFICATION_ENTER_TREE: {
			_stop_thread();
			if (!text.is_empty()) {