Method callback

packages/engine.io/lib/server.ts:791–817

(errorCode, errorContext)

    engineRequest.res = res;

    const callback: ErrorCallback = (errorCode, errorContext) => {
      if (errorCode !== undefined) {
        this.emit("connection_error", {
          req: engineRequest,
          code: errorCode,
          message: Server.errorMessages[errorCode],
          context: errorContext,
        });
        abortRequest(res, errorCode, errorContext);
        return;
      }

      if (engineRequest._query.sid) {
        debug("setting new request for existing client");
        this.clients[engineRequest._query.sid].transport.onRequest(
          engineRequest,
        );
      } else {
        const closeConnection = (errorCode, errorContext) =>
          abortRequest(res, errorCode, errorContext);
        this.handshake(
          engineRequest._query.transport as TransportName,
          engineRequest,
          closeConnection,
        );
      }
    };

    this._applyMiddlewares(engineRequest, res, (err) => {
      if (err) {