BUG/MINOR: connection: avoid null pointer dereference in send-proxy-v2

found by coverity.

[wt: this bug was introduced by commit 404d978 ("MINOR: add ALPN
 information to send-proxy-v2"). It might be triggered by a health
 check on a server using ppv2 or by an applet making use of such a
 server, if at all configurable].

This needs to be backported to 1.8.
1 file changed