Fix panic on empty params

bridge/irc/irc.go

@@ -234,6 +234,10 @@ func (b *Birc) handleNewConnection(client *girc.Client, event girc.Event) {
 }
 
 func (b *Birc) handleJoinPart(client *girc.Client, event girc.Event) {
+	if len(event.Params) == 0 {
+		flog.Debugf("handleJoinPart: empty Params? %#v", event)
+		return
+	}
 	channel := event.Params[0]
 	if event.Command == "KICK" {
 		flog.Infof("Got kicked from %s by %s", channel, event.Source.Name)