### Godot version

4.1.beta (7b1387ff2)

### System information

Mageia 9, Linux

### Issue description

When opening an empty project in latest `master`, I get these errors:
```
ERROR: Index p_idx = -1 is out of bounds (edited_scene.size() = 1).
   at: get_scene_path (editor/scu/../editor_data.cpp:880)
ERROR: Index p_idx = -1 is out of bounds (edited_scene.size() = 1).
   at: check_and_update_scene (editor/scu/../editor_data.cpp:683)
ERROR: Index p_idx = -1 is out of bounds (edited_scene.size() = 1).
   at: set_edited_scene (editor/scu/../editor_data.cpp:745)
```

Possibly related to recent changes to restore past sessions, but there's nothing to restore in this case?

### Steps to reproduce

- Create a new project, edit it
- Quit to project manager
- Re-open the newly created project -> errors

### Minimal reproduction project

Empty project.
project_run_bar->stop_playing();
}
void EditorNode::add_io_error(const String &p_error) {
	DEV_ASSERT(Thread::get_caller_id() == Thread::get_main_id());
	singleton->load_errors->add_image(singleton->gui_base->get_theme_icon(SNAME("Error"), SNAME("EditorIcons")));
	singleton->load_errors->add_text(p_error + "\n");
	EditorInterface::get_singleton()->popup_dialog_centered_ratio(singleton->load_error_dialog, 0.5);
}
bool EditorNode::_find_scene_in_use(Node *p_node, const String &p_path) const {
	if (p_node->get_scene_file_path() == p_path) {
		return true;
	}
	for (int i = 0; i < p_node->get_child_count(); i++) {
		if (_find_scene_in_use(p_node->get_child(i), p_path)) {
			return true;
		}
	}
	return false;
}
bool EditorNode::is_scene_in_use(const String &p_path) {
	Node *es = get_edited_scene();
	if (es) {
		return _find_scene_in_use(es, p_path);
	}
	return false;
}
OS::ProcessID EditorNode::has_child_process(OS::ProcessID p_pid) const {
	return project_run_bar->has_child_process(p_pid);
}
void EditorNode::stop_child_process(OS::ProcessID p_pid) {