HttpUtil::parseResponse fails on empty $response

[kaktus-74]

It can happen that $response will be empty string (sometimes on 404 error)

and line
list($rawHeader, $rawBody) = explode("\r\n\r\n", $response, 2);
will throw an exception
ErrorException: Undefined offset: 1 in \vendor\php-vcr\php-vcr\src\VCR\Util\HttpUtil.php on line 70