### 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 
return visible_characters;
}
int RichTextLabel::get_character_line(int p_char) {
	_validate_line_caches();
	int line_count = 0;
	int to_line = main->first_invalid_line.load();
	for (int i = 0; i < to_line; i++) {
		MutexLock lock(main->lines[i].text_buf->get_mutex());
		if (main->lines[i].char_offset < p_char && p_char <= main->lines[i].char_offset + main->lines[i].char_count) {
			for (int j = 0; j < main->lines[i].text_buf->get_line_count(); j++) {
				Vector2i range = main->lines[i].text_buf->get_line_range(j);
				if (main->lines[i].char_offset + range.x < p_char && p_char <= main->lines[i].char_offset + range.y) {
					return line_count;
				}
				line_count++;
			}
		} else {
			line_count += main->lines[i].text_buf->get_line_count();
		}
	}
	return -1;
}
int RichTextLabel::get_character_paragraph(int p_char) {