Crash in `BaseMessageListFragment.onSaveInstanceState`

[wmontwe]

We need to fix the top crash experienced in Beta 17.03b3:

Exception kotlin.UninitializedPropertyAccessException: lateinit property adapter has not been initialized
  at com.fsck.k9.ui.messagelist.BaseMessageListFragment.onSaveInstanceState (BaseMessageListFragment.kt:914)
  at androidx.fragment.app.Fragment.performSaveInstanceState (Fragment.java:3318)
  at androidx.fragment.app.FragmentStateManager.saveState (FragmentStateManager.java:723)
  at androidx.fragment.app.FragmentStore.saveActiveFragments (FragmentStore.java:217)
  at androidx.fragment.app.FragmentManager.saveAllStateInternal (FragmentManager.java:2724)
  at androidx.fragment.app.FragmentManager.lambda$attachController$5 (FragmentManager.java:3001)
  at androidx.savedstate.internal.SavedStateRegistryImpl.performSave$savedstate (SavedStateRegistryImpl.kt:139)
  at androidx.savedstate.SavedStateRegistryController.performSave (SavedStateRegistryController.android.kt:38)
  at androidx.activity.ComponentActivity.onSaveInstanceState (ComponentActivity.kt:350)
  at com.fsck.k9.activity.MessageHomeActivity.onSaveInstanceState (MessageHomeActivity.kt:635)
  at android.app.Activity.performSaveInstanceState (Activity.java:2559)
  at android.app.Instrumentation.callActivityOnSaveInstanceState (Instrumentation.java:1752)
  at android.app.ActivityThread.callActivityOnSaveInstanceState (ActivityThread.java:7401)
  at android.app.ActivityThread.callActivityOnStop (ActivityThread.java:6758)
  at android.app.ActivityThread.handleRelaunchActivityInner (ActivityThread.java:7341)
  at android.app.ActivityThread.handleRelaunchActivity (ActivityThread.java:7246)
  at android.app.servertransaction.ActivityRelaunchItem.execute (ActivityRelaunchItem.java:106)
  at android.app.servertransaction.ActivityTransactionItem.execute (ActivityTransactionItem.java:63)
  at android.app.servertransaction.TransactionExecutor.executeNonLifecycleItem (TransactionExecutor.java:133)
  at android.app.servertransaction.TransactionExecutor.executeTransactionItems (TransactionExecutor.java:103)
  at android.app.servertransaction.TransactionExecutor.execute (TransactionExecutor.java:80)
  at android.app.ActivityThread$H.handleMessage (ActivityThread.java:3150)
  at android.os.Handler.dispatchMessage (Handler.java:110)
  at android.os.Looper.loopOnce (Looper.java:273)
  at android.os.Looper.loop (Looper.java:363)
  at android.app.ActivityThread.main (ActivityThread.java:10060)
  at java.lang.reflect.Method.invoke
  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:632)
  at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:975)

[wmontwe]

The crash is caused by using lateinit for the MessageListAppearance. The MessageListFragment quickly cycles through its lifecycle during navigation, and when onSaveInstanceState is called, the adapter access crashes because it’s waiting for the MessageListAppearance to be emitted before it can be initialized.

I found #10382 as root cause. To fix the issue we need to revert #10382 and #10526 on beta.