<?php
/**
 * Mailgun plugin for CakePHP 3
 * Copyright (c) Narendra Vaghela (http://www.narendravaghela.com)
 *
 * Licensed under The MIT License
 * For full copyright and license information, please see the LICENSE.md
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright     Narendra Vaghela (http://www.narendravaghela.com)
 * @link          https://github.com/narendravaghela/cakephp-mailgun
 * @license       http://www.opensource.org/licenses/mit-license.php MIT License
 */
namespace MailgunEmail\Mailer\Exception;

use Cake\Core\Exception\Exception;

/**
 * Missing Credentials exception - used when API Key or Domain is not set.
 */
class MissingCredentialsException extends Exception
{

    /**
     * {@inheritDoc}
     */
    protected $_messageTemplate = 'Mailgun %s is not set.';

    /**
     * {@inheritDoc}
     */
//    public function __construct($message, $code = 404)
//    {
//        parent::__construct($message, $code);
//    }
}

<?php

/**
 * Mailgun plugin for CakePHP 3
 * Copyright (c) Narendra Vaghela (http://www.narendravaghela.com)
 *
 * Licensed under The MIT License
 * For full copyright and license information, please see the LICENSE.md
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright     Narendra Vaghela (http://www.narendravaghela.com)
 * @link          https://github.com/narendravaghela/cakephp-mailgun
 * @license       http://www.opensource.org/licenses/mit-license.php MIT License
 */

namespace MailgunEmail\Mailer\Exception;

use Cake\Core\Exception\Exception;

/**
 * Missing Credentials exception - used when API Key or Domain is not set.
 */
class MissingCredentialsException extends Exception
{

    /**
     * {@inheritDoc}
     */
    protected $_messageTemplate = 'Mailgun %s is not set.';

}

Remove commented code from exception
Remove commented code from exception
