### 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.
editor_layout_save_delay_timer->start();
}
void EditorNode::_dock_split_dragged(int ofs) {
	editor_layout_save_delay_timer->start();
}
void EditorNode::_load_editor_layout() {
	Ref<ConfigFile> config;
	config.instantiate();
	Error err = config->load(EditorPaths::get_singleton()->get_project_settings_dir().path_join("editor_layout.cfg"));
	if (err != OK) { 
		
		TreeItem *root = FileSystemDock::get_singleton()->get_tree_control()->get_item_with_metadata("res:", 0);
		if (root) {
			root->set_collapsed(false);
		}
		if (overridden_default_layout >= 0) {
			_layout_menu_option(overridden_default_layout);
		}
		return;
	}
	_load_docks_from_config(config, "docks");
	_load_open_scenes_from_config(config);
	_load_central_editor_layout_from_config(config);
	editor_data.set_plugin_window_layout(config);
}
void EditorNode::_update_dock_slots_visibility(bool p_keep_selected_tabs) {