net: fix error details in connect()

3ac49419 introduced a
bug as it attempted to access properties of an
undefined variable. This commit cleans up the offending
code.

Fixes: https://github.com/iojs/io.js/issues/510
PR-URL: https://github.com/iojs/io.js/pull/514


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>