### 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
#ifdef TOOLS_ENABLED
	if (Engine::get_singleton()->is_editor_hint()) {
		return;
	}
#endif
	if (spawn_node.is_valid()) {
		Node *node = Object::cast_to<Node>(ObjectDB::get_instance(spawn_node));
		if (node && node->is_connected("child_entered_tree", callable_mp(this, &MultiplayerSpawner::_node_added))) {
			node->disconnect("child_entered_tree", callable_mp(this, &MultiplayerSpawner::_node_added));
		}
	}
	Node *node = spawn_path.is_empty() && is_inside_tree() ? nullptr : get_node_or_null(spawn_path);
	if (node) {
		spawn_node = node->get_instance_id();
		if (get_spawnable_scene_count()) {
			node->connect("child_entered_tree", callable_mp(this, &MultiplayerSpawner::_node_added));
		}
	} else {
		spawn_node = ObjectID();
	}
}
void MultiplayerSpawner::_notification(int p_what) {