Why doesn't Laravel's custom exception work?

Question

Laravel

IndexController.php:

public function testException(){
        try{
            echo $test;
        }
        catch(Exception $e) {
                throw new 
 PostsInCategoryNotFoundErrorException($e);
        }

    }

PostsInCategoryNotFoundErrorException.php

namespace App\Exceptions;

use Exception;

class PostsInCategoryNotFoundErrorException extends Exception
{

}

handler.php

public function render($request, Exception $exception)
{
    if ($exception instanceof PostsInCategoryNotFoundErrorException) {
      echo 'Ошибка в переменной';
    }
    return parent::render($request, $exception);
}

It still gives its standard error page "Whoops, looks like something went wrong"