### 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.
bool ret_changed = false;
	List<PropertyInfo> pi;
	obj->get_property_list(&pi);
	for (const PropertyInfo &E : pi) {
		if (!(E.usage & PROPERTY_USAGE_STORAGE)) {
			continue;
		}
		switch (E.type) {
			case Variant::OBJECT: {
				Ref<Resource> res = obj->get(E.name);
				if (_find_and_save_resource(res, processed, flags)) {
					ret_changed = true;
				}
			} break;