longify: check if returning 200 OK crashes.

[shabble]

Error:

Can't use an undefined value as an ARRAY reference at /home/.../.irssi/scripts/autorun/63-longify-urls.pl line 186. the closest link to that that I can find is: Link: yfrog Photo : http://yfrog.com/kh4q7p

Appears that https://yfrog.com/kh4q7p is actually a valid (non-shortened) link.