This error occurs when viewing maps the first time when clicking a menu bar link to get to a page with a map:

ol.js:70 Uncaught TypeError: Cannot read property '0' of undefined
{{ at Fd.k.lf (ol.js:70)}}
{{ at ExploreMap.jsx:214}}
{{ at BasicMap.componentDidUpdate (BasicMap.jsx:150)}}

....

The error does not seem to occur when loading the page itself.

Note: Only occurs with the fix for the missing Features, so should use that code branch when investigating.