QP string issue

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
	queryParams: ['page', 'per_page']
});

helpers.my-helper.js

import Ember from 'ember';

export function myHelper(params/*, hash*/) {
  return Ember.typeOf(params[0]);
}

export default Ember.Helper.helper(myHelper);

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  actions: {
		queryParamsDidChange(changed, removed, all) {
			console.log(changed, removed, all);
    }
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
Try <a href="#?page=1&per_page=100"> apple</a>
<hr>
{{per_page}} = {{my-helper per_page}}
{{page}} = {{my-helper page}}
{{outlet}}
<br>
<br>

twiddle.json

{
  "version": "0.11.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.8.2",
    "ember-data": "2.11.0",
    "ember-template-compiler": "2.8.2",
    "ember-testing": "2.8.2"
  },
  "addons": {}
}