Rotating devices during startup causes crash

Steps to reproduce:

• fresh install of mailbox
• disable battery optimization using do-not-kill-me dialog
• continue to startup fragment
• rotate device

Crash:

2022-06-10 15:27:05.320 23832-23832/org.briarproject.mailbox E/AndroidRuntime: FATAL EXCEPTION: main
    Process: org.briarproject.mailbox, PID: 23832
    java.lang.IllegalArgumentException: Navigation action/destination org.briarproject.mailbox:id/action_doNotKillMeFragment_to_startupFragment cannot be found from the current destination Destination(org.briarproject.mailbox:id/startupFragment) label=StartupFragment class=org.briarproject.mailbox.android.ui.StartupFragment
        at androidx.navigation.NavController.navigate(NavController.kt:1536)
        at androidx.navigation.NavController.navigate(NavController.kt:1468)
        at androidx.navigation.NavController.navigate(NavController.kt:1926)
        at org.briarproject.mailbox.android.ui.MainActivity.onCreate$lambda-0(MainActivity.kt:68)