### 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.
ERR_FAIL_COND_V_MSG(p_class.is_empty(), nullptr, "Class name cannot be empty.");
	Ref<Script> scr;
	if (ScriptServer::is_global_class(p_class)) {
		scr = EditorNode::get_editor_data().script_class_load_script(p_class);
	}
	return _get_class_or_script_icon(p_class, scr, p_fallback);
}
bool EditorNode::is_object_of_custom_type(const Object *p_object, const StringName &p_class) {
	ERR_FAIL_COND_V(!p_object, false);
	Ref<Script> scr = p_object->get_script();
	if (scr.is_null() && Object::cast_to<Script>(p_object)) {
		scr = p_object;
	}
	if (scr.is_valid()) {
		Ref<Script> base_script = scr;
		while (base_script.is_valid()) {
			StringName name = EditorNode::get_editor_data().script_class_get_name(base_script->get_path());
			if (name == p_class) {
				return true;
			}
			base_script = base_script->get_base_script();
		}
	}
	return false;
}
void EditorNode::progress_add_task(const String &p_task, const String &p_label, int p_steps, bool p_can_cancel) {