Hello there! I'm trying to get the absolute minimum usage example working, and am running into an issue. I have tried on linux and mac, on firefox and chrome, and cannot get it to work.

Here is a code sandbox reproducing it:
https://codesandbox.io/s/exciting-surf-uos1hs?file=/src/App.js

You will see that the onResize function is being called with the new size, however, the width variable returned by useResizeObserver is not getting updated.