Function onError

packages/socket.io/client-dist/socket.io.js:4649–4660

(err)

        fn && fn();
      });
      var onError = function onError(err) {
        debug$1("error");
        _this2.cleanup();
        _this2._readyState = "closed";
        _this2.emitReserved("error", err);
        if (fn) {
          fn(err);
        } else {
          // Only do this if there is no fn to handle the error
          _this2.maybeReconnectOnOpen();
        }
      };
      // emit `error`
      var errorSub = on(socket, "error", onError);
      if (false !== this._timeout) {