Hi there, I am trying to use the scrollspy code from https://mdbootstrap.com/react/advanced/scrollspy/ My imports are below. import { Col, Container, Row, View, Mask, scrollSpySectionsOffset, ScrollSpyBox, ScrollSpyList, ScrollSpyListItem, ScrollSpyText} from 'mdbreact'; Getting the below error.   × TypeError: Cannot read property 'includes' of undefined ScrollRiseOfTechnology.componentDidMount src/components/pages/ScrollRiseOfTechnology.js:19

  16 | let scrollSpySections = this.scrollSpyText.getElementsByTagName('h4');
  17 | for (let i = 0; i < scrollSpySections.length; i++) {
  18 |   let currentOffsetTop = scrollSpySections[i].offsetTop - 16;
> 19 |   if (!scrollSpySectionsOffset.includes(currentOffsetTop)) {
  20 |     scrollSpySectionsOffset.push(currentOffsetTop);
  21 |   }
  22 | }

 

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