### Godot version

4.1.rc.custom_build. c83f912bc

### System information

Ubuntu 22.04 CI

### Issue description

When executing
```
extends Node
func _process(delta):

	var temp_variable35241 = RichTextLabel.new()
	add_child(temp_variable35241)
	temp_variable35241.set_fit_content(true)
	temp_variable35241.parse_bbcode("3188932498")
	temp_variable35241.queue_free()
```
this code freeze project in CI for at least 60 seconds

### Steps to reproduce

Above

### Minimal reproduction project

N/A
if ((int)p_frame->lines.size() - 1 <= p_frame->first_invalid_line) {
		p_frame->first_invalid_line = (int)p_frame->lines.size() - 1;
	}
}
void RichTextLabel::add_text(const String &p_text) {
	_stop_thread();
	MutexLock data_lock(data_mutex);
	if (current->type == ITEM_TABLE) {
		return; 
	}
	int pos = 0;
	while (pos < p_text.length()) {
		int end = p_text.find("\n", pos);
		String line;
		bool eol = false;
		if (end == -1) {
			end = p_text.length();
		} else {
			eol = true;
		}
		if (pos == 0 && end == p_text.length()) {
			line = p_text;
		} else {