Saveable state exception on transition

[HLCaptain]

I am writing Dialog logic into my app and noticed a strange crash when navigating back in Navigators in a Dialog.

Stack trace:

Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: Key illyan.butler.ui.login.LoginScreen:transition was used multiple times 
    at androidx.compose.runtime.saveable.SaveableStateHolderImpl$SaveableStateProvider$1$1.invoke(SaveableStateHolder.kt:89)
    at androidx.compose.runtime.saveable.SaveableStateHolderImpl$SaveableStateProvider$1$1.invoke(SaveableStateHolder.kt:88)
    at androidx.compose.runtime.DisposableEffectImpl.onRemembered(Effects.kt:82)
    at androidx.compose.runtime.CompositionImpl$RememberEventDispatcher.dispatchRememberObservers(Composition.kt:1295)
    at androidx.compose.runtime.CompositionImpl.applyChangesInLocked(Composition.kt:984)
    at androidx.compose.runtime.CompositionImpl.applyChanges(Composition.kt:1005)
    at androidx.compose.runtime.Recomposer$runRecomposeAndApplyChanges$2$1.invoke(Recomposer.kt:639)
    at androidx.compose.runtime.Recomposer$runRecomposeAndApplyChanges$2$1.invoke(Recomposer.kt:551)
    at androidx.compose.runtime.BroadcastFrameClock$FrameAwaiter.resume(BroadcastFrameClock.kt:42)
    at androidx.compose.runtime.BroadcastFrameClock.sendFrame(BroadcastFrameClock.kt:71)
    at androidx.compose.ui.scene.BaseComposeScene.render(BaseComposeScene.skiko.kt:163)
    at androidx.compose.ui.scene.ComposeSceneMediator$DesktopSkikoView.onRender(ComposeSceneMediator.desktop.kt:523)
    at org.jetbrains.skiko.SkiaLayer.update$skiko(SkiaLayer.awt.kt:548)
    at org.jetbrains.skiko.redrawer.AWTRedrawer.update(AWTRedrawer.kt:54)
    at org.jetbrains.skiko.redrawer.Direct3DRedrawer$frameDispatcher$1.invokeSuspend(Direct3DRedrawer.kt:49)
    at org.jetbrains.skiko.redrawer.Direct3DRedrawer$frameDispatcher$1.invoke(Direct3DRedrawer.kt)
    at org.jetbrains.skiko.redrawer.Direct3DRedrawer$frameDispatcher$1.invoke(Direct3DRedrawer.kt)
    at org.jetbrains.skiko.FrameDispatcher$job$1.invokeSuspend(FrameDispatcher.kt:33)
    at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
    at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:104)
    at java.desktop/java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:318)
    at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:773)
    at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:720)
    at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:714)
    at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
    at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
    at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:742)
    at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
    at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
    at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
    at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
    at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

Reproduce the problem:

• clone this commit
• Setup local.properties from README.md
• Run desktop app
• Click on profile on right top
• Click on login (twice because it is buggy)
• Click on select host (just to transition on another screen)
• Press escape to go back
• Press escape to go back (again)
• Crash happens

I suspect, that the problem lies in Navigator::saveableState somewhere.

[HLCaptain]

As I investigate the problem even more, it looks like, that the Login screen is added twice due to the 2 clicks needed to transition to the screen. So for some reason, the first transition just does not happen, even though the screen is created and pushed to the stack.

Fixed version available here. Notice, how I have to replace all stack items when initializing the Navigator with the starting screen to "enforce" later transitions in Dialog.kt.

LaunchedEffect(Unit) {
    nav.replaceAll(startScreen)
}