title: "v.context.$implicit.categories[0] is undefined" error in Ionic 3
body: <p>I am trying to access the category slug for a product in ionic using the WordPress rest API. This seems to work fine on one page as <code>&lt;h3 class="product-name uppercase"&gt;{{productdetail?.categories[0].slug}}&lt;/h3&gt;</code> however this does not seems to work when i try implementing the same using for loop in angular on another page </p>
  
  <pre><code>&lt;div class="width50" *ngFor="let object of dataList"&gt;
      &lt;img src="{{object.images[0].src}}" width="150"  (click)="navigateToPage(object.id)" /&gt;
      &lt;h3 class="product-name uppercase" text-nowrap&gt;{{object?.categories[0].slug}}&lt;/h3&gt; 
  &lt;/div&gt;
  </code></pre>
  
  <p>it gives an error as <code>v.context.$implicit.categories[0] is undefined</code> however on same page the code for image source seems to work fine.</p>