### 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.
int flg = 0;
	if (EDITOR_GET("filesystem/on_save/compress_binary_resources")) {
		flg |= ResourceSaver::FLAG_COMPRESS;
	}
	flg |= ResourceSaver::FLAG_REPLACE_SUBRESOURCE_PATHS;
	HashSet<String> edited_resources;
	int saved = 0;
	List<Ref<Resource>> cached;
	ResourceCache::get_cached_resources(&cached);
	for (Ref<Resource> res : cached) {
		if (!res->is_edited()) {
			continue;
		}
		String path = res->get_path();
		if (path.begins_with("res:")) {
			int subres_pos = path.find("::");
			if (subres_pos == -1) {
				
				edited_resources.insert(path);
			} else {
				edited_resources.insert(path.substr(0, subres_pos));
			}
		}