code: function _handleReturnMessage(id, method) {
                  var callback = this.callbackCache.get(id, true);
                  var args = method && method.args;
  
                  if ("function" === typeof callback) {
                      // First try to parse the first parameter in case the error is an object
                      if (args && args.length && args[0] && "Error" === args[0].type && "string" === typeof args[0].message) {
                          args[0] = new Error(args[0].message);
                      }
  
                      try {
                          callback.apply(null, args);
                      }
                      catch (ex) {
                          PostMessageUtilities.log("Error while trying to handle the returned message from request/command", "ERROR", "PostMessageCourier");
                      }
                  }
              }
docs: Method for handling return messages from the callee
  @param {String} id - the id of the callback
  @param {Object} method - the method object with needed args
  @private