Error: count(): Argument #1 ($value). When using form builder type collection

I’m using library kristijanhusak/laravel-form-builder and having a problem with ONE TO ONE (Polymorphic). It shows error “count(): Argument 1 ($value) must be of type Countable|array, MekongdeltaSlugModelsSlug given” like image bellow.

enter image description here

This is my database structure.

posts

  • id – integer
  • name – string

slugs

  • id – integer
  • url – string
  • sluggable_id – integer
  • sluggable_type – string

This is my buildForm
enter image description here

Trait sluggable and model Post
enter image description here

My environment

PHP 8.2

Laravel 10.25

“kris/laravel-form-builder”: “dev-master”,

I don’t know where I made a mistake or am missing something, can you help me?
Sorry for my English.
Thank you very much,

I want it to appear as a slug in the input text