IssueTracker

• Jetpack Compose release version: 1.0.0-alpha09
• Android Studio Build: 4.2 Canary 16

Steps to Reproduce:

1. Import and run the attached project
2. Tap the navigation icon in the app bar

Expected Results: An exception mentioning something to the effect of "perhaps you forgot to provide a scaffoldState to Scaffold()".

Actual Results: An exception saying "The target value must have an associated anchor":

    Process: com.commonsware.compose.sampler.simplescaffold, PID: 26730
    java.lang.IllegalArgumentException: The target value must have an associated anchor.
        at androidx.compose.material.SwipeableState.animateTo(Swipeable.kt:289)
        at androidx.compose.material.SwipeableState.animateTo$default(Swipeable.kt:283)
        at androidx.compose.material.DrawerState.open(Drawer.kt:128)
        at androidx.compose.material.DrawerState.open$default(Drawer.kt:127)
        at com.commonsware.compose.scaffold.issue.MainActivityKt$TopBar$2$1$1.invoke(MainActivity.kt:62)

The sample has a bug, where scaffoldState is not supplied to a Scaffold() for which we are setting up a drawer:

@Composable
private fun SimpleScaffold() {
  val scaffoldState = rememberScaffoldState()

  Scaffold(
    /*scaffoldState = scaffoldState, -- TODO restore this line*/
    topBar = { TopBar(scaffoldState) },
    drawerContent = { DrawerContent(scaffoldState) },
  ) {

  }
}

If you uncomment that line, the sample works as expected.

However, with the app bug in place... that exception is really obscure.

IMHO, ideally, Scaffold() does a bit more sanity-checking and provides a more focused exception for this mistake. If that proves to be impractical, maybe you could add some additional prose to the existing exception text to hint to the developer where the problem might be.

Scaffold() is likely to be popular, which means the more n00b-friendly it can be, the better off we are (again IMHO).

Thanks for considering this!