### 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
if (!get_multiplayer()->has_multiplayer_peer() || !is_multiplayer_authority()) {
		return;
	}
	if (tracked_nodes.has(p_node->get_instance_id())) {
		return;
	}
	const Node *parent = get_spawn_node();
	if (!parent || p_node->get_parent() != parent) {
		return;
	}
	int id = find_spawnable_scene_index_from_path(p_node->get_scene_file_path());
	if (id == INVALID_ID) {
		return;
	}
	const String name = p_node->get_name();
	ERR_FAIL_COND_MSG(name.validate_node_name() != name, vformat("Unable to auto-spawn node with reserved name: %s. Make sure to add your replicated scenes via 'add_child(node, true)' to produce valid names.", name));
	_track(p_node, Variant(), id);
}
NodePath MultiplayerSpawner::get_spawn_path() const {