### 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
switch (p_what) {
		case NOTIFICATION_POST_ENTER_TREE: {
			_update_spawn_node();
		} break;
		case NOTIFICATION_EXIT_TREE: {
			_update_spawn_node();
			for (const KeyValue<ObjectID, SpawnInfo> &E : tracked_nodes) {
				Node *node = Object::cast_to<Node>(ObjectDB::get_instance(E.key));
				ERR_CONTINUE(!node);
				node->disconnect(SceneStringNames::get_singleton()->tree_exiting, callable_mp(this, &MultiplayerSpawner::_node_exit));
				get_multiplayer()->object_configuration_remove(node, this);
			}
			tracked_nodes.clear();
		} break;
	}
}
void MultiplayerSpawner::_node_added(Node *p_node) {