Bad Request at respond node_modules/elasticsearch/src/lib/transport.js:264:15 - node.js

Question

I am very dummy on ElasticSearch and I have little experience with NodeJs. I have created few cruds using NodeJs + MongoDb. I have to change from MongoDb to ElasticSearch (this is mandatory). Please, I don't want to compare MOngoDb with ElasticSearch so don't try that.
I am following the example found here
https://blog.raananweber.com/2015/11/24/simple-autocomplete-with-elasticsearch-and-node-js/
I have started succesfully ElasticSearch. I can see:
nodejs express.js-elasticsearch-autocomplete-demo-master # curl --noproxy -XGET 'http://127.0.0.1:9200/?pretty'
{
"name" : "-em7X-s",
"cluster_name" : "elasticsearch",
"cluster_uuid" : "cqJUaPcFREe4wX_YyYWoFg",
"version" : {
"number" : "5.2.1",
"build_hash" : "db0d481",
"build_date" : "2017-02-09T22:05:32.386Z",
"build_snapshot" : false,
"lucene_version" : "6.4.1"
},
"tagline" : "You Know, for Search"
}
However, when I try to start the sample above or access I get the error bellow respectvely:
/dev/samples/express.js-elasticsearch-autocomplete-demo-master $ npm start
> autocompleter#0.0.0 start /home/demetrio/dev/samples/express.js-elasticsearch-autocomplete-demo-master
> node ./bin/www
Elasticsearch INFO: 2017-02-16T20:00:48Z
Adding connection to http://localhost:9200/
Unhandled rejection Error: Bad Request
at respond (/home/demetrio/dev/samples/express.js-elasticsearch-autocomplete-demo-master/node_modules/elasticsearch/src/lib/transport.js:264:15)
at checkRespForFailure (/home/demetrio/dev/samples/express.js-elasticsearch-autocomplete-demo-master/node_modules/elasticsearch/src/lib/transport.js:223:7)
at HttpConnector.<anonymous> (/home/demetrio/dev/samples/express.js-elasticsearch-autocomplete-demo-master/node_modules/elasticsearch/src/lib/connectors/http.js:155:7)
at IncomingMessage.wrapper (/home/demetrio/dev/samples/express.js-elasticsearch-autocomplete-demo-master/node_modules/lodash/index.js:3095:19)
at emitNone (events.js:72:20)
at IncomingMessage.emit (events.js:166:7)
at endReadableNT (_stream_readable.js:905:12)
at nextTickCallbackWith2Args (node.js:441:9)
at process._tickCallback (node.js:355:17)
Unhandled rejection Error: [illegal_argument_exception] request [/randomindex/_suggest] contains unrecognized parameter: [type]
at respond (/home/demetrio/dev/samples/express.js-elasticsearch-autocomplete-demo-master/node_modules/elasticsearch/src/lib/transport.js:264:15)
at checkRespForFailure (/home/demetrio/dev/samples/express.js-elasticsearch-autocomplete-demo-master/node_modules/elasticsearch/src/lib/transport.js:223:7)
at HttpConnector.<anonymous> (/home/demetrio/dev/samples/express.js-elasticsearch-autocomplete-demo-master/node_modules/elasticsearch/src/lib/connectors/http.js:155:7)
at IncomingMessage.wrapper (/home/demetrio/dev/samples/express.js-elasticsearch-autocomplete-demo-master/node_modules/lodash/index.js:3095:19)
at emitNone (events.js:72:20)
at IncomingMessage.emit (events.js:166:7)
at endReadableNT (_stream_readable.js:905:12)
at nextTickCallbackWith2Args (node.js:441:9)
at process._tickCallback (node.js:355:17)
Unhandled rejection Error: [illegal_argument_exception] request [/randomindex/_suggest] contains unrecognized parameter: [type]
at respond (/home/demetrio/dev/samples/express.js-elasticsearch-autocomplete-demo-master/node_modules/elasticsearch/src/lib/transport.js:264:15)
at checkRespForFailure (/home/demetrio/dev/samples/express.js-elasticsearch-autocomplete-demo-master/node_modules/elasticsearch/src/lib/transport.js:223:7)
at HttpConnector.<anonymous> (/home/demetrio/dev/samples/express.js-elasticsearch-autocomplete-demo-master/node_modules/elasticsearch/src/lib/connectors/http.js:155:7)
at IncomingMessage.wrapper (/home/demetrio/dev/samples/express.js-elasticsearch-autocomplete-demo-master/node_modules/lodash/index.js:3095:19)
at emitNone (events.js:72:20)
at IncomingMessage.emit (events.js:166:7)
at endReadableNT (_stream_readable.js:905:12)
at nextTickCallbackWith2Args (node.js:441:9)
at process._tickCallback (node.js:355:17)
I am very confused what to check. Any suggestion will be appreciated. My final target is to understand how to connect to ElasticSearch from NodeJs application