### 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.
Node *old_edited_scene_root = get_editor_data().get_edited_scene_root();
	if (old_edited_scene_root) {
		if (old_edited_scene_root->get_parent() == scene_root) {
			scene_root->remove_child(old_edited_scene_root);
		}
		old_edited_scene_root->disconnect(SNAME("replacing_by"), callable_mp(this, &EditorNode::set_edited_scene));
	}
	get_editor_data().set_edited_scene_root(p_scene);
	if (Object::cast_to<Popup>(p_scene)) {
		Object::cast_to<Popup>(p_scene)->show();
	}
	SceneTreeDock::get_singleton()->set_edited_scene(p_scene);
	if (get_tree()) {
		get_tree()->set_edited_scene_root(p_scene);
	}
	if (p_scene) {
		if (p_scene->get_parent() != scene_root) {
			scene_root->add_child(p_scene, true);
		}
		p_scene->connect(SNAME("replacing_by"), callable_mp(this, &EditorNode::set_edited_scene));
	}
}
int EditorNode::_get_current_main_editor() {