:question: What is supposed to happen if `async {}` block throws an exception, but the result is nev...

# coroutines

[voddan]

❓ What is supposed to happen if async {} block throws an exception, but the result is never used? I get different behaviour in playground and InteliJ
https://pl.kotl.in/rkOAdiNiQ

suspend fun main() {
    coroutineScope {
        val x = async { null!! }
    }
    
    println("end")
}

[gildor]

What is result that you expect. Behavior of playground the same as should be for async according to docs

[gildor]

Await encapsulate exception and do not throwing it until someone calls await

[voddan]

@gildor I use coroutines_version = '0.30.2-eap13' and this example propagates the exception up into my bash

[Daniel Tam]

I believe this behaviour changed recently to be the same as launch, because otherwise it's painful to await multiple async calls correctly while still stopping if an error occurs anywhere

[voddan]

@Daniel Tam do you know where could I read about it?

[Daniel Tam]

https://github.com/Kotlin/kotlinx.coroutines/releases/tag/0.30.0

[voddan]

👍🏼

[gildor]

Ahhh, sure, coroutineScope will throw an error anyway, because failed async will cancel coroutineScope

[voddan]

BTW, how do I revert to the old behaviour? I don't care about the error until I need the result

[gildor]

You can use Supervision scope, as I understand
https://github.com/Kotlin/kotlinx.coroutines/blob/master/docs/exception-handling.md#supervision