Access Auth::user() in route.php

I'm having a problem in accessing the Auth::user() in my route.php. So far here's what i've got:

Route::group(['middleware' => 'auth'], function () {
    if(Auth::user()->role == "manager"){
        Route::get('/','ManagerController@index');
    }
    else if(Auth::user()->role == "rater"){
        Route::get('/','RaterController@index');
    }
});

It gives me this error "Trying to get property of non-object" whenever I try to use the Auth::user()->role

via Chebli Mohamed