brain.js: Value1.concat is not a function error

Hi Guys I Just started Exploring brain.js and facing some issue

const brain                 = require('brain.js');
const faker                 = require('faker');
const co                    = require('co');



let payload = [];

const generateData = function () { 
    return new Promise((resolve,reject) => {
        const result = {input: {
            color:  faker.commerce.color(),
            price:  faker.commerce.price()
        },  output: { [faker.commerce.product()] : 1 } }
        return resolve(result);
    })
}

for (let index = 0; index < 100; index++) {
    payload.push(generateData());
}

Promise.all(payload).then(result => {
    console.log(result);
    var net = new brain.recurrent.LSTM();
    net.train(result)
    var output = net.run({ color: faker.commerce.color, price: faker.commerce.price });
    console.log(output);
})

Above is My Code where i am trying to Generate Some Fake eCommerce Data of Product with price and color attribute and output as a name of product

But i am getting following Error

UnhandledPromiseRejectionWarning: TypeError: value1.concat is not a function
    at DataFormatter.toIndexesInputOutput (F:\demo\brain.js-demo\node_modules\brain.js\dist\utilities\data-formatter.js:103:40)
    at LSTM.formatDataIn (F:\demo\brain.js-demo\node_modules\brain.js\dist\recurrent\rnn.js:766:35)
    at LSTM.setupData (F:\demo\brain.js-demo\node_modules\brain.js\dist\recurrent\rnn.js:750:26)
    at LSTM.train (F:\demo\brain.js-demo\node_modules\brain.js\dist\recurrent\rnn.js:460:21)
    at Promise.all.then.result (F:\demo\brain.js-demo\server.js:26:9)
    at <anonymous>
    at process._tickCallback (internal/process/next_tick.js:188:7)
    at Function.Module.runMain (module.js:695:11)
    at startup (bootstrap_node.js:191:16)
    at bootstrap_node.js:612:3
(node:12504) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch
block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:12504) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

Can Anyone Help me out Understanding What am i Doing Wrong in my code ???