Added error handling for a bad default network.
Added error handling for a bad default network.

ProgVal/Limnoria-test,jeffmahoney/supybot,mazaclub/mazabot-core,kblin/supybot-gsoc,prashantpawar/supybot-rothbot,raboof/supybot,haxwithaxe/supybot,Ban3/Limnoria,ProgVal/Limnoria-test,Ban3/Limnoria,mazaclub/mazabot-core,frumiousbandersnatch/supybot-code,buildbot/supybot