### 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.
}
						save_confirmation->reset_size();
						save_confirmation->popup_centered();
						break;
					}
					_discard_changes();
					break;
				}
				if (save_each) {
					tab_closing_menu_option = current_menu_option;
					for (int i = 0; i < editor_data.get_edited_scene_count(); i++) {
						tabs_to_close.push_back(editor_data.get_scene_path(i));
					}
					_proceed_closing_scene_tabs();
				} else {
					String unsaved_scenes;
					int i = _next_unsaved_scene(true, 0);
					while (i != -1) {
						unsaved_scenes += "\n            " + editor_data.get_edited_scene_root(i)->get_scene_file_path();
						i = _next_unsaved_scene(true, ++i);
					}
					if (p_option == RELOAD_CURRENT_PROJECT) {
						save_confirmation->set_ok_button_text(TTR("Save & Reload"));
						save_confirmation->set_text(TTR("Save changes to the following scene(s) before reloading?") + unsaved_scenes);
					} else {
						save_confirmation->set_ok_button_text(TTR("Save & Quit"));
						save_confirmation->set_text((p_option == FILE_QUIT ? TTR("Save changes to the following scene(s) before quitting?") : TTR("Save changes to the following scene(s) before opening Project Manager?")) + unsaved_scenes);
					}
					save_confirmation->reset_size();
					save_confirmation->popup_centered();