why i am getting No query results for model in laravel?

When i search by city name which is available in my database table it will show the result but when i search by unknown city which is not available in my database table it says -No query results for model [App\City]. i am sharing you the code and screenshot see error screenshot actually i want to redirect to 401 page if the city is not found in my database table

Here is my route

Route::get('teacher-jobs-by-city/{city}','TeacherJobsController@by_location');

Here is my function

public function by_location($location_id='') {

$data= array();
$location = City::where('slug',$location_id)->where('status','1')->firstOrFail();
$items= Subject::orderBy('id','asc')->get();
$data['location']=$location;

      //$subjects = [''=>'Select Subject'] + Subject::lists('subject_title','id')->toArray();
      //$city = [''=>'Select City'] + City::lists('name','id')->toArray();
        $active_class ='Select Subject to see job Openings';
        return view('frontend.teacherjobs.by_location',compact('active_class','data','items'));

    }

via Chebli Mohamed