Wierd behavior with each

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  length: 6,
  originalVal: '',
  arrayVal: Ember.computed('originalVal', function() {
    const origin = this.get('originalVal').toString();
    const len = this.get('length');
    let arr = new Array(len);
    for (let i = 0; i < len; i++) {
      arr[i] = origin.charAt(i) || '';
    }
    return arr;
  })
});

templates.application.hbs

<p>Input string please(max {{length}} chars): {{input value=originalVal maxLength=length}}</p>
<p>Conversed string: {{arrayVal}}</p>
{{#each arrayVal as |v index|}}
  	<p>{{index}}:{{v}}</p>
{{/each}}

twiddle.json

{
  "version": "0.10.7",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.10.0",
    "ember-data": "2.10.0",
    "ember-template-compiler": "2.10.0",
    "ember-testing": "2.10.0"
  },
  "addons": {}
}