Cannot read property 'getAttribute' of null on ion-slide with zoom attribute

i am getting Cannot read property ‘getAttribute’ of null error when used zoom attribute in ion-slides.Please suggest me about this issue.

Make sure whatever you’re calling getAttribute() isn’t null when you are doing so.

@rapropos in fallowing code I used Zoom=“true” but not working on zooming and the same error appears.

<ion-slides pager="true" style="height:35%" dir="rtl" zoom="true">
  <ion-slide *ngFor="let images of post.attachLists ">
    <img src="{{images.filename}}">