regarding to vfs adapter error

gistfile1.txt

###############################################################
> server/index.js

const {
  Core,
  CoreServiceProvider,
  PackageServiceProvider,
  VFSServiceProvider,
  AuthServiceProvider,
  SettingsServiceProvider
} = require('@osjs/server');

const config = require('./config.js');
const osjs = new Core(config, {});
const monsterAdapter = require('./vfs/monster-adapter')

osjs.register(CoreServiceProvider, {before: true});
osjs.register(PackageServiceProvider);
osjs.register(VFSServiceProvider);
osjs.register(AuthServiceProvider);
osjs.register(SettingsServiceProvider);

osjs.register(VFSServiceProvider,{
          args:{
              adapters:{
                    monster: monsterAdapter
                  }
            }
});

###############################################################
> server/config.js

const path = require('path');
const root = path.resolve(__dirname, '../../');

module.exports = {
  root,
  port: 8000,
  public: path.resolve(root, 'dist'),
  vfs:{
     mountpoints:[{
           name: 'myMonster',
           adapter: 'monster',
           attributes: {
                           connection:{}
                         }
         }]
   }

};


###############################################################
> client/config.js

export default {
  auth: {
    login: {
      username: 'demo',
      password: 'demo'
    }
  },

  vfs: {
    defaultPath: 'myMonster:/',
    mountpoints: [{
                  name: 'myMonster',
                  label: 'Monster Drive'
                }]
  }
};

this is the error

server side error

src/server/vfs/monster-adapter.js

....
....
module.exports = (core) => {
const mon = new Monster("http://myendpoint:8000/auth/v1.0")
mon.login('test:tester', 'testing')
console.log("Hello Monster!")

return {
    readdir: vfs => (monster) => readdir(monster, mon),
    mkdir: vfs => (monster) => mkdir(monster, mon),
    readfile: vfs => (monster, options) => readfile(monster, options, mon),
    writefile: vfs => (monster, options) => writefile(monster, options, mon),
    unlink: vfs => (monster) => unlink(monster, mon),
    copy: vfs => (from, to) => copy(from, to, mon),
    rename: vfs => (from, to, options) => rename(from, to, options, mon),
}

};