Trying to use elasticsearch from a koa app

server.js

var app, distDir, elClient, koa, path, router, send;

path = require('path');

send = require('koa-send');

router = require('koa-router')();

koa = require('koa');

app = koa();

elClient = new elasticsearch.Client({
  log: 'error',
  keepAlive: true
});

router.get('/api/what', function*(next) {
  var genify, res, search;
  genify = require('thunkify-wrap').genify;
  search = genify(elClient.search);
  res = (yield search({
    index: 'my-index',
    q: 'what'
  }));
  return this.body = {
    answer: "you send " + res
  };
});

app.use(router.routes());

distDir = __dirname + '/../client/dist';

app.use(function*(next) {
  return (yield send(this, this.path, {
    root: distDir
  }));
});

app.listen(3000);