### 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 
String txt;
	ERR_FAIL_COND_V(p_frame == nullptr, txt);
	ERR_FAIL_COND_V(p_line < 0 || p_line >= (int)p_frame->lines.size(), txt);
	Line &l = p_frame->lines[p_line];
	Item *it_to = (p_line + 1 < (int)p_frame->lines.size()) ? p_frame->lines[p_line + 1].from : nullptr;
	int end_idx = 0;
	if (it_to != nullptr) {
		end_idx = it_to->index;
	} else {
		for (Item *it = l.from; it; it = _get_next_item(it)) {
			end_idx = it->index + 1;
		}
	}
	for (Item *it = l.from; it && it != it_to; it = _get_next_item(it)) {
		if (it->type == ITEM_TABLE) {
			ItemTable *table = static_cast<ItemTable *>(it);
			for (Item *E : table->subitems) {
				ERR_CONTINUE(E->type != ITEM_FRAME); 
				ItemFrame *frame = static_cast<ItemFrame *>(E);
				for (int i = 0; i < (int)frame->lines.size(); i++) {
					txt += _get_line_text(frame, i, p_selection);
				}
			}
		}