My /etc/resolv.conf was wiped by Network Manager (gee, thanks), so
ircd.js was throwing the following unhelpful exceptions when starting
up:
Feb 25 13:47:51 git jsexec[19108]: !JavaScript : uncaught exception: Unable to create any sockets
Feb 25 13:47:51 git jsexec[19108]: !JavaScript : uncaught exception: Unable to create any sockets

First, instead of throwing a string, throw an Error object so we can
actually know where the exception ocurred. Please, everyone, throw Errors
not Strings.

Second, throw a different more helpful exception if there are no nameservers
specified in the DNS constructor or configured on the system.