Finding ResizeObserver with Typescript in Angular 9

I am trying to implement a ResizeObserver in an Angular app:

const obs = new ResizeObserver(e => {
      // ...
});

... and am met with the TS error:

TS2304: Cannot find name 'ResizeObserver'.

I've tried to update my type definition with:

@types/resize-observer-browser

... however my issue persists. Is there an advisable solution or common workaround, or would it be better to use an NPM package like 'resize-observer' to keep moving forward?

Happy to include more info if needed.

Tks!