Crash when opening a thread - `IndexOutOfBoundsException`

[krzysdz]

Checklist

• I have used the search function to see if someone else has already submitted the same bug report.
• I will describe the problem with as much detail as possible.

App

Thunderbird for Android

App version

12.0b1

Where did you get the app from?

Other

Android version

13 (xiaomi.eu 14.0.3.0.TJUMIXM)

Device model

Xiaomi POCO X3 Pro (global)

Steps to reproduce

1. Make sure that "Threaded view" in "General settings" -> "Display" is enabled
2. Click on a message thread in any folder in any account (doesn't matter if it's a regular or "Unified" account)

Expected behavior

A message list with messages from the selected thread opens.

Actual behavior

App crashes on folderId = search.folderIds[0], because folderIds is empty (see log below).

Logs

[2025-07-18 13:47:05.570 Uid(value=10012):21172:21172 E/AndroidRuntime]
FATAL EXCEPTION: main
Process: net.thunderbird.android.beta, PID: 21172
java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
	at java.util.ArrayList.get(ArrayList.java:437)
	at com.fsck.k9.activity.MessageList.configureDrawer(MessageList.kt:1508)
	at com.fsck.k9.activity.MessageList.initializeFromLocalSearch(MessageList.kt:1472)
	at com.fsck.k9.activity.MessageList.showThread(MessageList.kt:1259)
	at com.fsck.k9.ui.messagelist.MessageListFragment.onMessageClicked(MessageListFragment.kt:664)
	at com.fsck.k9.ui.messagelist.MessageListAdapter.messageClickedListener$lambda$12(MessageListAdapter.kt:196)
	at com.fsck.k9.ui.messagelist.MessageListAdapter.$r8$lambda$XacPqseepY5pvvIbl17RaYQDtNw(MessageListAdapter.kt:0)
	at com.fsck.k9.ui.messagelist.MessageListAdapter$$ExternalSyntheticLambda0.onClick(R8$$SyntheticClass:0)
	at android.view.View.performClick(Unknown Source:17)
	at android.view.View.performClickInternal(Unknown Source:3)
	at android.view.View.-$$Nest$mperformClickInternal(Unknown Source:0)
	at android.view.View$PerformClick.run(Unknown Source:8)
	at android.os.Handler.handleCallback(Unknown Source:2)
	at android.os.Handler.dispatchMessage(Unknown Source:4)
	at android.os.Looper.loopOnce(Unknown Source:182)
	at android.os.Looper.loop(Unknown Source:82)
	at android.app.ActivityThread.main(Unknown Source:123)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(Unknown Source:11)
	at com.android.internal.os.ZygoteInit.main(Unknown Source:312)

[krzysdz]

I think it's caused by commit e260360 (#9433), because previously singleFolderMode was false and the branch accessing search.folderIds[0] was not executed.

EDIT: git bisect also points to this commit

[rafaeltonholo]

Hi @krzysdz, thanks for the report! I will investigate the root cause and provide a fix for the crash soon!

[krzysdz]

I've just tested #9472 and the app no longer crashes.

[rafaeltonholo]

[Approval Request Comment]
Pull request: #9272
Regression caused by (issue #): #9433
User impact if declined: The user won't be able to open the Threaded view if the setting is enabled
Testing completed (on daily, etc.): Testing completed by the reporter via pull request. I will retest again once available on Daily or Beta
Risk to taking this patch (and alternatives if risky): N/A

[coreycb]

Hi, this is a small fix but really should spend some time getting tested on daily before we uplift. We can cut another beta next Monday that includes this, if testing goes well. For now I'm going to remove the beta uplift label.