### 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 (font_it) {
					if (font_it->font.is_valid()) {
						font = font_it->font;
					}
					if (font_it->font_size > 0) {
						font_size = font_it->font_size;
					}
				}
				ItemFontSize *font_size_it = _find_font_size(it);
				if (font_size_it && font_size_it->font_size > 0) {
					font_size = font_size_it->font_size;
				}
				l.text_buf->add_string("\n", font, font_size);
				txt += "\n";
				l.char_count++;
				remaining_characters--;
			} break;
			case ITEM_TEXT: {
				ItemText *t = static_cast<ItemText *>(it);
				Ref<Font> font = p_base_font;
				int font_size = p_base_font_size;
				ItemFont *font_it = _find_font(it);
				if (font_it) {
					if (font_it->font.is_valid()) {
						font = font_it->font;
					}
					if (font_it->font_size > 0) {
						font_size = font_it->font_size;
					}
				}