Opening a tcp connection to a down host results in NIL on LW 6

[quicklisp]

Per Ala'a Mohammad Alawi:

Hi Zach

quicklisp implementation of open-connection for LispWorks uses
open-tcp-stream. which will fail silently (returning nil) in case of
unkwon-host (a site was down). adding :errorp to the call will help
the user by show a readable error message. I've tried sbcl and ccl
where both the error was more indicative than complaining about a
stream being a 'nil' (as was the case with Lispworks)

Verify that the :errorp option works on each version of LispWorks and update the code to use it.

[quicklisp]

This is an easy fix with :errorp, just do it!