ember-focus-trapper bug

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

templates.application.hbs

{{#focus-trapper disable=false cycle=true}}
  <form action="">
    <label>You must fill out this input field: <input type="text"></label>
    <label>And this input field: <input type="text"></label>
    <button tabindex="0">
      <span tabindex="-1">
        button
      </span>
    </button>
  </form>
{{/focus-trapper}}

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2",
    "ember-focus-trapper": "0.0.1"
  }
}