handle bad packet more correctly

lib/tcpd.js

@@ -27,9 +27,10 @@ module.exports.create = function (cli, dnsd) {
 
         // TODO pad two bytes for lengths
         dnsd.onMessage(nb, function (err, newAb, dbgmsg) {
-          var lenbuf = Buffer.from([ newAb.length >> 8, newAb.length & 255 ]);
           // TODO XXX generate legit error packet
           if (err) { console.error("Error", err); c.end(); return; }
+
+          var lenbuf = Buffer.from([ newAb.length >> 8, newAb.length & 255 ]);
           console.log('TCP ' + dbgmsg);
 
           c.write(lenbuf);