### 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.
show_accept(
							vformat(TTR("The current scene has no root node, but %d modified external resource(s) were saved anyway."), saved),
							TTR("OK"));
				} else if (p_option == FILE_SAVE_AS_SCENE) {
					
					show_accept(
							TTR("A root node is required to save the scene. You can add a root node using the Scene tree dock."),
							TTR("OK"));
				}
				break;
			}
			file->set_file_mode(EditorFileDialog::FILE_MODE_SAVE_FILE);
			List<String> extensions;
			Ref<PackedScene> sd = memnew(PackedScene);
			ResourceSaver::get_recognized_extensions(sd, &extensions);
			file->clear_filters();
			for (int i = 0; i < extensions.size(); i++) {
				file->add_filter("*." + extensions[i], extensions[i].to_upper());
			}
			if (!scene->get_scene_file_path().is_empty()) {
				String path = scene->get_scene_file_path();
				file->set_current_path(path);
				if (extensions.size()) {
					String ext = path.get_extension().to_lower();
					if (extensions.find(ext) == nullptr) {
						file->set_current_path(path.replacen("." + ext, "." + extensions.front()->get()));
					}
				}
			} else if (extensions.size()) {
				String root_name = scene->get_name();