protected function writeToExceptionLogFile($message)
    {
        if (is_writable($this->exceptionLogFile) || is_writable(dirname($this->exceptionLogFile))) {
            $message = sprintf('[%s] %s' . PHP_EOL, (new \DateTime())->format(\DateTime::ISO8601), $message);
            @file_put_contents($this->exceptionLogFile, $message, FILE_APPEND);
        }
    }