### 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
#include "multiplayer_spawner.h"
#include "core/io/marshalls.h"
#include "scene/main/multiplayer_api.h"
#include "scene/main/window.h"
#include "scene/scene_string_names.h"
#ifdef TOOLS_ENABLED
bool MultiplayerSpawner::_set(const StringName &p_name, const Variant &p_value) {
	if (p_name == "_spawnable_scene_count") {
		spawnable_scenes.resize(p_value);
		notify_property_list_changed();
		return true;
	} else {
		String ns = p_name;
		if (ns.begins_with("scenes/")) {
			uint32_t index = ns.get_slicec('/', 1).to_int();
			ERR_FAIL_UNSIGNED_INDEX_V(index, spawnable_scenes.size(), false);
			spawnable_scenes[index].path = p_value;
			return true;
		}
	}
	return false;
}
bool MultiplayerSpawner::_get(const StringName &p_name, Variant &r_ret) const {