Hey there, I wonder if anyone here can help me. I ...

# announcements

[Max Spencer]

Hey there, I wonder if anyone here can help me. I am doing some work with Kotlin Multiplatform and am running into this kind of exception:

kotlin.native.IncorrectDereferenceException: Trying to access top level value not marked as @ThreadLocal or @SharedImmutable from non-main thread

The context is quite convoluted and I'm not sure if it is relevant or not. I can elaborate further if anyone thinks it might help, but briefly:

I've created a Kotlin Multiplatform library (see https://github.com/guardian/multiplatform-ophan) which can send various "events" to an analytics service called "Ophan".
I've come up with a way to implement "Native Modules" for React Native applications using shared Kotlin Multiplatform code (see https://github.com/guardian/react-native-with-kotlin)
Now I'm trying to put these two ideas together. But unfortunately, although the multiplatform-ophan library works as expected when consumed directly from Android or iOS, I run into the above exception on iOS when it is included in a React Native app via this extra layer of indirection.

I don't expect anyone to help me debug this issue if it's anything to do with React Native and I appreciate you might think this seems like a very odd combination of things to be doing. But even just some general pointers about the kind of pitfalls you might expect in this area would be greatly appreciated.

[Max Spencer]

One lead/idea is that it's something to do with Charsets.UTF_8, due to this stack trace:

kotlin.native.IncorrectDereferenceException: Trying to access top level value not marked as @ThreadLocal or @SharedImmutable from non-main thread
        ... kfun:kotlinx.io.charsets.encodeToByteArrayImpl1$[e-mail].(kotlin.CharSequence;kotlin.Int;kotlin.Int)kotlin.ByteArray + 443
       ...

and the fact that we are trying to do this at the point where it crashes:

val bytes = str.toByteArray(Charsets.UTF_8)

Could it be due to Charsets.UTF_8 lacking the @SharedImmutable annotation?