IR compiler: can't extend JS classes

I’ve just spent a few days migrating my app to the IR compiler because Kotlin Serialization wasn’t working properly under the legacy compiler.

After that, I’ve now realised that my whole React app relies on the legacy feature that you can extend JS classes in Kotlin. Doing so under the IR compiler leads to ClassCastExceptions.

Now contemplating what hack I can write under the hood to bridge the gap. But I’m a little frustrated to say the least: writing such hacks seems part of the Kotlin/JS experience for me – but this seems a bigger gap between the languages than before.

Any thoughts would be welcome.