Throw an exception for a cURL multi response if needed
int $code Curl response code:
private function checkCurlResult($code) {
if ($code != CURLM_OK && $code != CURLM_CALL_MULTI_PERFORM) {
throw new CurlException(isset($this->multiErrors[$code]) ? "cURL error: {$code} ({$this->multiErrors[$code][0]}): cURL message: {$this->multiErrors[$code][1]}" : 'Unexpected cURL error: ' . $code);
}
}