Duplicate className property warnings/errors

[bklop]

I recently upgraded a project that use Feliz.Bulma to Webpack 5 and Fable 3 beta. After the upgrade I get lots of React warnings about duplicate className properties when running in development mode:

Error: Property className is duplicated
    at createObjDebug (Util.js?e456:467)
    at eval (DashBoard.js?807b:500)
    at renderWithHooks (react-dom.development.js?61bb:14985)
    ...

I think this is due to Helpers.combineClasses not filtering out the duplicate className properties (it only combines them into a new classes property).