### 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.
}
	singleton->editor_plugins_over->remove_plugin(p_editor);
	singleton->editor_plugins_force_over->remove_plugin(p_editor);
	singleton->editor_plugins_force_input_forwarding->remove_plugin(p_editor);
	singleton->remove_child(p_editor);
	singleton->editor_data.remove_editor_plugin(p_editor);
	for (KeyValue<ObjectID, HashSet<EditorPlugin *>> &kv : singleton->active_plugins) {
		kv.value.erase(p_editor);
	}
}
void EditorNode::add_extension_editor_plugin(const StringName &p_class_name) {
	ERR_FAIL_COND_MSG(!ClassDB::class_exists(p_class_name), vformat("No such editor plugin registered: %s", p_class_name));
	ERR_FAIL_COND_MSG(!ClassDB::is_parent_class(p_class_name, SNAME("EditorPlugin")), vformat("Class is not an editor plugin: %s", p_class_name));
	ERR_FAIL_COND_MSG(singleton->editor_data.has_extension_editor_plugin(p_class_name), vformat("Editor plugin already added for class: %s", p_class_name));
	EditorPlugin *plugin = Object::cast_to<EditorPlugin>(ClassDB::instantiate(p_class_name));
	singleton->editor_data.add_extension_editor_plugin(p_class_name, plugin);
	add_editor_plugin(plugin);
}
void EditorNode::remove_extension_editor_plugin(const StringName &p_class_name) {
	
	if (singleton->exiting) {
		return;
	}
	ERR_FAIL_COND_MSG(!singleton->editor_data.has_extension_editor_plugin(p_class_name), vformat("No editor plugin added for class: %s", p_class_name));
	EditorPlugin *plugin = singleton->editor_data.get_extension_editor_plugin(p_class_name);
	remove_editor_plugin(plugin);
	memfree(plugin);
	singleton->editor_data.remove_extension_editor_plugin(p_class_name);
}
void EditorNode::_update_addon_config() {