nickserv: Fix help display

irc/client.go

 	}
 	lines := wordWrap(text, limit)
 
+	// force blank lines to be sent if we receive them
+	if len(lines) == 0 {
+		lines = []string{""}
+	}
+
 	for _, line := range lines {
 		client.Send(nil, client.server.name, "NOTICE", client.nick, line)
 	}

irc/nickserv.go

 		}
 
 		client.Notice(client.t("Could not login with your TLS certificate or supplied username/password"))
+	} else {
+		client.Notice(client.t("Command not recognised. To see the available commands, run /NS HELP"))
 	}
 }