Zone.assertZonePatched is not a function
<p>I am getting the error message:</p>

<p>Unhandled Promise rejection: Zone.assertZonePatched is not a function</p>

<p>Although I am importing zonejs correctly in index.html:</p>

<pre><code>  &lt;script src="https://unpkg.com/zone.js@0.6.17/dist/zone.js"&gt;&lt;/script&gt;
</code></pre>

<p>Here is the code:</p>

<p>Plnkr: <a href="http://plnkr.co/edit/zZYOcgxcRINx23JhuxOk?p=preview">http://plnkr.co/edit/zZYOcgxcRINx23JhuxOk?p=preview</a></p>

<p>What is wrong here?</p>