### 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 
Item *indentable = p_item;
	while (indentable) {
		if (indentable->type == ITEM_INDENT || indentable->type == ITEM_LIST) {
			return indentable;
		}
		indentable = indentable->parent;
	}
	return indentable;
}
RichTextLabel::ItemFont *RichTextLabel::_find_font(Item *p_item) {
	Item *fontitem = p_item;
	while (fontitem) {
		if (fontitem->type == ITEM_FONT) {
			ItemFont *fi = static_cast<ItemFont *>(fontitem);
			switch (fi->def_font) {
				case NORMAL_FONT: {
					if (fi->variation) {
						Ref<FontVariation> fc = fi->font;
						if (fc.is_valid()) {
							fc->set_base_font(theme_cache.normal_font);
						}
					} else {
						fi->font = theme_cache.normal_font;
					}
					if (fi->def_size) {
						fi->font_size = theme_cache.normal_font_size;
					}
				} break;
				case BOLD_FONT: {
					if (fi->variation) {