ProductRepository.php

<?php

namespace App\Repositories;

use App\Models\Product;
use MrAtiebatie\Repository;
use Illuminate\Database\Eloquent\Model;

/**
 * Product repository
 */
class ProductRepository extends Model
{
    use Repository;

    /**
     * The model being queried.
     *
     * @var \Illuminate\Database\Eloquent\Model
     */
    protected $model;

    /**
     * Constructor
     */
    public function __construct()
    {
        $this->model = app(Product::class);
    }

    /**
     * Find published products by SKU
     * @param  {int} $sku
     * @return {Product}
     */
    public function findBySku(int $sku): Product {
        return this->whereIsPublished(1)
                   ->whereSku($sku)
                   ->first();
    }
}

Missing a $ there https://gist.github.com/MrAtiebatie/9e0a22f6cf132d6f17837d5ee28e1d49#file-productrepository-php-L37
;)

@felipefrancisco

Ahh came here to notice that :)