Funny, I've been looking for something like this, without knowing that I was really.

Unfortunately I am getting "Content rendering error An unhandled error occurred in the application. We apologize for the inconvenience!" for the HTML, CSS and JS references.

edit: That appears to be a bigger issue which has been discussed for some time by a few people (https://github.com/zealdocs/zeal/issues/1155).

  find ~/.local/share/Zeal/Zeal/docsets -name "react-main.*.js" -exec rm -rf {} \;

here's a fix that worked for me on Manjaro (Linux) for the time being.