protected function handleError($body)
{
$firstMessage = $this->getFirstMessage($body);
$error = 'An error occurred. Nexmo status code: ' . $firstMessage['status'];
if ($this->hasProperty($firstMessage, 'error-text')) {
$error = $firstMessage['error-text'];
}
$this->throwNotSentException($error, $firstMessage['status']);
}