if query has no rows in laravel 5 through AJAX call, "readyState": 4 is appearing in console

i have a query in my laravel 5 application that fetches some data from table. When there is data in table then it is showing data on screen, but if table has now row against query, then "readyState": 4 error is showing in console. my code looks like below.

public function some_function($accId){
    $q = DB::Select("SELECT ca.*, ch.* FROM credit_accounts as ca, credit_history as ch WHERE ch.acc_id=ca.id AND ch.acc_id='$accId' ORDER BY ch.acc_id DESC");

    if (count($q) > 0){
      // if query fetch some data, then this if condition works fine
      $val="condition true";
    }
    else{
      // if there is no data against this query then else block not runs and return "readyState": 4 error. but it should return "condition false".
      $val = "condition false";
    }

      return $val;
}

via Chebli Mohamed