Cannot read property 'outlets' of null in Angular 4 : <p>I have Angular 4.3.6 project where a template snippet produces this error.</p>

<p>Template block:</p>

<p><code>&lt;a [routerLink]="['/article',article?.id]"&gt;{{article?.title}}&lt;/a&gt;</code></p>

<p>Error stack trace:</p>

<pre><code>ArticleSpComponent.html:26 ERROR TypeError: Cannot read property 'outlets' of null
    at createNewSegmentGroup (router.es5.js:2967)
    at updateSegmentGroup (router.es5.js:2896)
    at router.es5.js:2914
    at forEach (router.es5.js:593)
    at updateSegmentGroupChildren (
</code></pre>

<p>The error cause seems to be obvious. article variable is fetched async from Http and initialized after page is rendered so firstly it's null. However I thought that putting ? after this variable allows to avoid this issue.</p>

<p>Can you please advise?</p>
