retry loop grabbing a folder of files via adb

gistfile1.js

var Promise = require('bluebird')
var fs = require('fs')
var adb = require('adbkit')
var client = adb.createClient()

const pathToFiles = '/sdcard/Download';

const loop = () => {
  client.listDevices()
  .then(function(devices) {
    const device = devices[0];
    return client.readdir(device.id, pathToFiles)
    .then(function(files) {
      if(!files.length) throw new Error("no files")
      console.log("THIS MANY LEFT: "+files.length)
      const allFiles = files.filter( file => file.isFile() )
      const thresholds = [];
      for(var x=0, len = allFiles.length; x< len; x+=5 ){
        thresholds.push(x);
      }
      return Promise.mapSeries( thresholds, x => Promise.map( allFiles.slice(x,x+5), file => {
        console.log("pulling file: "+file.name)
        console.log(file)
        return client.pull(device.id, pathToFiles+'/'+file.name)
          .then(function(transfer) {
            return (new Promise(function(resolve, reject) {
              var fn = __dirname + '/tmp/download/' + file.name;
              transfer.on('end', function() {
                console.log('[%s] Pull complete', device.id)
                resolve(true)
              })
              transfer.on('error', reject)
              transfer.pipe(fs.createWriteStream(fn))
            })).then( () => {
              console.log("stat: "+file.name)
              return client.shell(device.id, "rm \""+pathToFiles+"/"+file.name+"\"")              
                .then(adb.util.readAll)
                .then(function(output) {
                  console.log('[%s] %s', device.id, output.toString().trim())
                })
            })
          })

      }))

    })

  })
  .then(function(res) {
    console.log('Done pulling all files!')
  })
  .catch(function(err) {
    console.error('Something went wrong:', err.stack)

    setTimeout( loop, 2000 )
  })  
}

loop();