Mutation of exception that thrown from another scope

[ihostage]

Describe the bug

Handling of exception in my app is breaked by Debug mode (JVM -ea option). Is it expected (by design) and I need to be ready of this mutation of thrown exceptions or is it a bug?

Provide a Reproducer

import kotlinx.coroutines.coroutineScope
import kotlinx.coroutines.runBlocking

fun main() = runBlocking {
    try {
        throwEx()
    } catch (e: Exception) {
        processException(e)
    }
    try {
        throwExFromNewScope()
    } catch (e: Exception) {
        processException(e)
    }
}

private fun processException(e: Throwable) {
    if (e is IllegalStateException && e.cause is IllegalArgumentException) {
        println("Got correctly exception: IllegalStateException <- IllegalArgumentException")
    } else {
        e.printStackTrace()
    }
}

private suspend fun throwExFromNewScope() = coroutineScope {
    throwEx()
}

private suspend fun throwEx() {
    throw IllegalStateException(IllegalArgumentException("error"))
}

The code above works ok without Debug mode:

Got correctly exception: IllegalStateException <- IllegalArgumentException
Got correctly exception: IllegalStateException <- IllegalArgumentException

and throw an exception with -ea option

Got correctly exception: IllegalStateException <- IllegalArgumentException
java.lang.IllegalStateException: java.lang.IllegalArgumentException: error
	at WebFaultReproducer.throwEx(WebFaultReproducer.kt:32)
	at WebFaultReproducer.access$throwEx(WebFaultReproducer.kt:1)
	at WebFaultReproducer$throwExFromNewScope$2.invokeSuspend(WebFaultReproducer.kt:28)
	at WebFaultReproducer$throwExFromNewScope$2.invoke(WebFaultReproducer.kt)
	at WebFaultReproducer$throwExFromNewScope$2.invoke(WebFaultReproducer.kt)
	at kotlinx.coroutines.intrinsics.UndispatchedKt.startUndspatched(Undispatched.kt:66)
	at kotlinx.coroutines.intrinsics.UndispatchedKt.startUndispatchedOrReturn(Undispatched.kt:43)
	at kotlinx.coroutines.CoroutineScopeKt.coroutineScope(CoroutineScope.kt:286)
	at WebFaultReproducer.throwExFromNewScope(WebFaultReproducer.kt:27)
	at WebFaultReproducer.access$throwExFromNewScope(WebFaultReproducer.kt:1)
	at WebFaultReproducer$main$1.invokeSuspend(WebFaultReproducer.kt:13)
	at _COROUTINE._BOUNDARY._(CoroutineDebugging.kt:42)
	at WebFaultReproducer$main$1.invokeSuspend(WebFaultReproducer.kt:13)
Caused by: java.lang.IllegalStateException: java.lang.IllegalArgumentException: error
	at WebFaultReproducer.throwEx(WebFaultReproducer.kt:32)
	at WebFaultReproducer.access$throwEx(WebFaultReproducer.kt:1)
	at WebFaultReproducer$throwExFromNewScope$2.invokeSuspend(WebFaultReproducer.kt:28)
	at WebFaultReproducer$throwExFromNewScope$2.invoke(WebFaultReproducer.kt)
	at WebFaultReproducer$throwExFromNewScope$2.invoke(WebFaultReproducer.kt)
	at kotlinx.coroutines.intrinsics.UndispatchedKt.startUndspatched(Undispatched.kt:66)
	at kotlinx.coroutines.intrinsics.UndispatchedKt.startUndispatchedOrReturn(Undispatched.kt:43)
	at kotlinx.coroutines.CoroutineScopeKt.coroutineScope(CoroutineScope.kt:286)
	at WebFaultReproducer.throwExFromNewScope(WebFaultReproducer.kt:27)
	at WebFaultReproducer.access$throwExFromNewScope(WebFaultReproducer.kt:1)
	at WebFaultReproducer$main$1.invokeSuspend(WebFaultReproducer.kt:13)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:34)
	at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:100)
	at kotlinx.coroutines.EventLoopImplBase.processNextEvent(EventLoop.common.kt:263)
	at kotlinx.coroutines.BlockingCoroutine.joinBlocking(Builders.kt:94)
	at kotlinx.coroutines.BuildersKt__BuildersKt.runBlocking(Builders.kt:70)
	at kotlinx.coroutines.BuildersKt.runBlocking(Unknown Source)
	at kotlinx.coroutines.BuildersKt__BuildersKt.runBlocking$default(Builders.kt:48)
	at kotlinx.coroutines.BuildersKt.runBlocking$default(Unknown Source)
	at WebFaultReproducer.main(WebFaultReproducer.kt:6)
	at WebFaultReproducer.main(WebFaultReproducer.kt)
Caused by: java.lang.IllegalArgumentException: error
	... 21 more

[dkhalanskyjb]

Yes, this is expected. This is part of the stacktrace recovery mechanism: https://github.com/Kotlin/kotlinx.coroutines/blob/master/docs/topics/debugging.md#stacktrace-recovery-machinery
Please use Stack Overflow or the Kotlinlang Slack for usage questions.