message: Properly set default callback in callRpc
diff: @@ -206,7 +206,7 @@ exports.broadcast = (topic, message, callback) => {
  /*
  * Calls remotely the 'method' function defined in rpcPublic of 'to'.
  */
  -exports.callRpc = (to, method, args, callbacks = {}, timeout = TIMEOUT) => {
  +exports.callRpc = (to, method, args, callbacks = { callback: () => {} }, timeout = TIMEOUT) => {
  corrID += 1;
  map[corrID] = {};
  map[corrID].fn = callbacks;
  