[https-proxy-agent] Socket returned without TLS upgrade on non-200 CONNECT response, allowing request data to be sent over unencrypted connection

I would like to report a man-in-the-middle vulnerability in `https-proxy-agent`. It allows an attacker with access to the network firewall or targeted proxy server to obtain secrets (e.g. a HTTP basic auth header) from the client trying to send HTTPS traffic via HTTP proxy.

CONNECT www.google.com:443 HTTP/1.1
Host: www.google.com
Connection: close