### 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.
break;
			case 4:
				EditorScale::set_scale(1.5);
				break;
			case 5:
				EditorScale::set_scale(1.75);
				break;
			case 6:
				EditorScale::set_scale(2.0);
				break;
			default:
				EditorScale::set_scale(EDITOR_GET("interface/editor/custom_display_scale"));
				break;
		}
	}
	
	Window *w = Object::cast_to<Window>(SceneTree::get_singleton()->get_root());
	if (w) {
		w->set_min_size(Size2(1024, 600) * EDSCALE);
	}
	EditorFileDialog::set_default_show_hidden_files(EDITOR_GET("filesystem/file_dialog/show_hidden_files"));
	EditorFileDialog::set_default_display_mode((EditorFileDialog::DisplayMode)EDITOR_GET("filesystem/file_dialog/display_mode").operator int());
	int swap_cancel_ok = EDITOR_GET("interface/editor/accept_dialog_cancel_ok_buttons");
	if (swap_cancel_ok != 0) { 
		
		AcceptDialog::set_swap_cancel_ok(swap_cancel_ok == 2);
	}
	ResourceLoader::set_abort_on_missing_resources(false);
	ResourceLoader::set_error_notify_func(&EditorNode::add_io_error);
	ResourceLoader::set_dependency_error_notify_func(&EditorNode::_dependency_error_report);