Can't retrieve relation

In OrientDB community-2.0 I created 2 classes countries and cities with relation hasOne through Has property. The related record creates and relation exists. However I can't retrieve related record neother from Country model nor from City. Instead I get following error in Tinker log: Array to string conversion

Tinker log:

☁  laravel  php artisan tinker
Psy Shell v0.5.2 (PHP 5.5.20 — cli) by Justin Hileman
>>> $country = App\Country::create(['id' => 100, 'name' => 'Cyprus']);
=> App\Country {#776
     id: "#13:0",
     name: "Cyprus",
     updated_at: "2015-11-01 13:09:35",
     created_at: "2015-11-01 13:09:35",
   }
>>> $city = new App\City(['id' => 10, 'name' => 'Limassol']);
=> App\City {#789
     id: 10,
     name: "Limassol",
   }
>>> $relation = $country->has_city()->save($city);
=> Sgpatil\Orientdb\Eloquent\Edges\EdgeOut {#797}
>>> $city;
=> App\City {#789
     id: "#14:0",
     name: "Limassol",
     Has: "#13:0",
     updated_at: "2015-11-01 13:09:46",
     created_at: "2015-11-01 13:09:46",
   }
>>> $city->country;
PHP error:  Array to string conversion in /Users/dalamar/Documents/projects/orient/laravel/vendor/laravel/framework/src/Illuminate/Database/Grammar.php on line 39
>>> $country;
=> App\Country {#776
     id: "#13:0",
     name: "Cyprus",
     updated_at: "2015-11-01 13:09:35",
     created_at: "2015-11-01 13:09:35",
   }
>>> $country->cities;
PHP error:  Array to string conversion in /Users/dalamar/Documents/projects/orient/laravel/vendor/laravel/framework/src/Illuminate/Database/Grammar.php on line 39
>>> $country->has_city;
PHP error:  Array to string conversion in /Users/dalamar/Documents/projects/orient/laravel/vendor/laravel/framework/src/Illuminate/Database/Grammar.php on line 39

My models classes code:

Country

<?php

namespace App;

use Sgpatil\Orientdb\Eloquent\Model;

class Country extends Model
{
    protected $guarded = [];

    public function cities()
    {
        return $this->hasMany('App\City', 'Has');
    }

    public function has_city()
    {
        return $this->hasOne('App\City', 'Has');
    }
}

City

<?php

namespace App;

use Sgpatil\Orientdb\Eloquent\Model;

class City extends Model
{
    protected $guarded = [];

    public function country()
    {
        return $this->belongsTo('App\Country', 'Has');
    }
}

sgpatil / oriquent

Can't retrieve relation #8