whmcsKerioEmail/app/Helpers/ErrorCodesLib.php

<?php

namespace ModulesGarden\Servers\KerioEmail\App\Helpers;

use \ModulesGarden\Servers\KerioEmail\Core\HandlerError\ErrorCodes\ErrorCodes;

class ErrorCodesLib extends ErrorCodes
{
    const YOUR_APP_000001 = [
        self::MESSAGE => 'Your error message',
        self::CODE => 'YOUR_APP_000001',
        self::DEV_MESSAGE => "Your error message left for other developers, the error genesis explanation...",
        self::LOG => true //optional, determines if the error should be logged despite of inactive debug mode 
    ];       
}