Function onError

client-dist/socket.io.js:4125–4135

(err)

          fn && fn();
        });
        var onError = function onError(err) {
          _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) {