Preview thumbnail/image on Index after upload on filament panel posts

Hello everybody, I create an admin panel with filament and I try to retrieve an thumbnail/image on Index page. I call getMedia from spatia but show me Call to a member function getMedia() on null. The thumbnail column in database on posts table is empty but the media table the image exist. If you want any code just reply...

Edit: I make some changes. I try to load the first thumbnail for the first post and get image with getMedia but data is empty.

Spatie\MediaLibrary\MediaCollections\Models\Collections\MediaCollection {#1534 ▼ // app/Http/Controllers/HomeController.php:20
  +collectionName: "default"
  +formFieldName: null
  #items: []
  #escapeWhenCastingToString: false
}

code: $posts[0]->getMedia()