value1.concat error - brain.js

var fs = require('fs')
var brain = require('brain.js')

var bPath = "Z:\\Development\\Javascript\\NodeJS\\Neural Networks\\Brain.JS\\002\\src\\dataset\\business"
var tPath = "Z:\\Development\\Javascript\\NodeJS\\Neural Networks\\Brain.JS\\002\\src\\dataset\\tech"
var sample = "Z:\\Development\\Javascript\\NodeJS\\Neural Networks\\Brain.JS\\002\\src\\dataset\\011.txt"

var net = new brain.recurrent.LSTM()

var bFiles = fs.readdirSync(bPath)
var outputs = []

for (var i = 0; i < 4; i++) {
    var file = bFiles[i]

    var content = fs.readFileSync(bPath + "\\" + file)
    
    outputs.push({input: content, output: 'business' })
}

var tFiles = fs.readdirSync(tPath)

for (var i = 0; i < 4; i++) {
    var file = tFiles[i]

    var content = fs.readFileSync(tPath + "\\" + file)
    
    outputs.push({input: content, output: 'technology' })
}

console.log("training on " + outputs.length + " inputs ...")
net.train(outputs, { 
    log: true
})

var testFile = fs.readFileSync(sample)

var output = net.run(testFile);
console.log(output)