title: Laravel 5.5 Type error: Argument 1 passed to Illuminate\Auth\EloquentUserProvider::validateCredentials() must be an instance
body: <p>In my LoginController under Auth, I have used the following codes:</p>
  
  <pre><code>namespace App\Http\Controllers\Auth;
  
  use App\Model\Admin;
  use App\Http\Controllers\Controller;
  use Illuminate\Foundation\Auth\AuthenticatesUsers;
  use Illuminate\Http\Request;
  use Illuminate\Support\Facades\Input;
  use Illuminate\Support\Facades\Validator;
  use Illuminate\Support\Facades\Redirect;
  use Hash;
  use Auth;
  use DB;
  use App\Model\UserAdmin;
  
  class LoginController extends Controller {
  use AuthenticatesUsers;
  public function __construct() {
          $this-&gt;middleware('guest')-&gt;except('logout');
      }
  
  public function doLogin(Request $request) {
  $userdata = array(
              'email' =&gt; Input::get('email'),
              'password' =&gt; Input::get('password'),
              'status' =&gt; '1',
          );
  if (Auth::guard('admin')-&gt;attempt($userdata)) {
    return Redirect::intended('/administrator/dashboard')-&gt;with('successMessage', 'You have successfully logged in.');
  }
  }
  }
  </code></pre>
  
  <p>And in UserAdmin (model) under app/Model is as follows:</p>
  
  <pre><code>namespace App\Model;
  
  use Illuminate\Database\Eloquent\Model;
  use Illuminate\Support\Facades\DB;
  use Illuminate\Foundation\Auth\User as Authenticatable;
  use Config;
  class UserAdmin extends Authenticatable {
  protected $table = 'adminusers';
      public $timestamps = false;
      protected $fillable = ['firstName', 'lastName', 'email', 'company', 'website'];
  
      public function __construct() {
          parent::__construct(); // Don't forget this, you'll never know what's being done in the constructor of the parent class you extended
      }
  
  }
  </code></pre>
  
  <p>After submitting the login details, it shows me the error:</p>
  
  <blockquote>
    <p>Type error: Argument 1 passed to Illuminate\Auth\EloquentUserProvider::validateCredentials() must be an instance of Illuminate\Contracts\Auth\Authenticatable, instance of App\Model\UserAdmin given, called in /var/www/html/XXXXXX/vendor/laravel/framework/src/Illuminate/Auth/SessionGuard.php on line 379</p>
  </blockquote>