### Godot version

4.1.beta.a83eb16fb

### System information

Arch Linux

### Issue description

When attempting to have a scene load a resource that uses a script that exports a var of Callable type, a parse error will occur due to Callable not being serializable.

### Steps to reproduce

Create new project.
create a resource script that exports a Callable type:

```
class_name BreakStuff
extends Resource
@export var something: Callable
```

create a .tres file that uses the script.

create a scene that uses that resource, such as with a script like

```
extends Node
@export var stuff: Resource
```

set that resource to that .tres file.

close project and reopen.

Be greeted with error message about a parse error and be unable to open that scene.

Within plain text of .tscn file you can see a line that reads
something =

which causes a parse error as something has nothing to be set to.



### Minimal reproduction project

N/A
return spawn_path;
}
void MultiplayerSpawner::set_spawn_path(const NodePath &p_path) {
	spawn_path = p_path;
	_update_spawn_node();
}
void MultiplayerSpawner::_track(Node *p_node, const Variant &p_argument, int p_scene_id) {
	ObjectID oid = p_node->get_instance_id();
	if (!tracked_nodes.has(oid)) {
		tracked_nodes[oid] = SpawnInfo(p_argument.duplicate(true), p_scene_id);
		p_node->connect(SceneStringNames::get_singleton()->tree_exiting, callable_mp(this, &MultiplayerSpawner::_node_exit).bind(p_node->get_instance_id()), CONNECT_ONE_SHOT);
		_spawn_notify(p_node->get_instance_id());
	}
}
void MultiplayerSpawner::_spawn_notify(ObjectID p_id) {
	get_multiplayer()->object_configuration_add(ObjectDB::get_instance(p_id), this);
}
void MultiplayerSpawner::_node_exit(ObjectID p_id) {
	Node *node = Object::cast_to<Node>(ObjectDB::get_instance(p_id));
	ERR_FAIL_COND(!node);
	if (tracked_nodes.has(p_id)) {
		tracked_nodes.erase(p_id);
		get_multiplayer()->object_configuration_remove(node, this);
	}
}
int MultiplayerSpawner::find_spawnable_scene_index_from_path(const String &p_scene) const {