### 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 
_stop_thread();
	MutexLock data_lock(data_mutex);
	if (current->type == ITEM_TABLE) {
		return;
	}
	ItemNewline *item = memnew(ItemNewline);
	item->line = current_frame->lines.size();
	_add_item(item, false);
	current_frame->lines.resize(current_frame->lines.size() + 1);
	_invalidate_current_line(current_frame);
	queue_redraw();
}
bool RichTextLabel::remove_paragraph(const int p_paragraph) {
	_stop_thread();
	MutexLock data_lock(data_mutex);
	if (p_paragraph >= (int)current_frame->lines.size() || p_paragraph < 0) {
		return false;