### 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.
if (p_res.is_null()) {
		return false;
	}
	if (processed.has(p_res)) {
		return processed[p_res];
	}
	bool changed = p_res->is_edited();
	p_res->set_edited(false);
	bool subchanged = _find_and_save_edited_subresources(p_res.ptr(), processed, flags);
	if (p_res->get_path().is_resource_file()) {
		if (changed || subchanged) {
			ResourceSaver::save(p_res, p_res->get_path(), flags);
		}
		processed[p_res] = false; 
		return false;
	} else {
		processed[p_res] = changed;
		return changed;
	}
}
bool EditorNode::_find_and_save_edited_subresources(Object *obj, HashMap<Ref<Resource>, bool> &processed, int32_t flags) {