Crash when trying to open an encrypted draft without having a crypto provider configured

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 version

6.309

Where did you get the app from?

Google Play

Android version

Android 13

Device model

No response

Steps to reproduce

1. Put an encrypted message in your drafts folder
2. Try to open the encrypted draft message without having a crypto provider configured

Expected behavior

Display an error message

Actual behavior

Crash

Logs

Stack trace (via Google Play Developer Console):

Exception java.lang.NullPointerException: Attempt to invoke interface method 'java.util.Iterator java.util.List.iterator()' on a null object reference
  at com.fsck.k9.activity.compose.AttachmentPresenter.loadAllAvailableAttachments (AttachmentPresenter.java:210)
  at com.fsck.k9.activity.MessageCompose.processDraftMessage (MessageCompose.java:1399)
  at com.fsck.k9.activity.MessageCompose.processSourceMessage (MessageCompose.java:1272)
  at com.fsck.k9.activity.MessageCompose.loadLocalMessageForDisplay (MessageCompose.java:1669)
  at com.fsck.k9.activity.MessageCompose$11.onMessageViewInfoLoadFinished (MessageCompose.java:1689)
  at com.fsck.k9.activity.MessageLoaderHelper.onDecodeMessageFinished (MessageLoaderHelper.java:401)
  at com.fsck.k9.activity.MessageLoaderHelper.access$1100 (MessageLoaderHelper.java:76)
  at com.fsck.k9.activity.MessageLoaderHelper$3.onLoadFinished (MessageLoaderHelper.java:437)
  at com.fsck.k9.activity.MessageLoaderHelper$3.onLoadFinished (MessageLoaderHelper.java:414)
  at androidx.loader.app.LoaderManagerImpl$LoaderObserver.onChanged (LoaderManagerImpl.java:250)
  at androidx.lifecycle.LiveData.considerNotify (LiveData.java:133)
  at androidx.lifecycle.LiveData.dispatchingValue (LiveData.java:151)
  at androidx.lifecycle.LiveData.setValue (LiveData.java:309)
  at androidx.lifecycle.MutableLiveData.setValue (MutableLiveData.java:50)
  at androidx.loader.app.LoaderManagerImpl$LoaderInfo.setValue (LoaderManagerImpl.java:189)
  at androidx.loader.app.LoaderManagerImpl$LoaderInfo.onLoadComplete (LoaderManagerImpl.java:174)
  at androidx.loader.content.Loader.deliverResult (Loader.java:132)
  at com.fsck.k9.ui.message.LocalMessageExtractorLoader.deliverResult (LocalMessageExtractorLoader.java:47)
  at com.fsck.k9.ui.message.LocalMessageExtractorLoader.deliverResult (LocalMessageExtractorLoader.java:16)
  at androidx.loader.content.AsyncTaskLoader.dispatchOnLoadComplete (AsyncTaskLoader.java:258)
  at androidx.loader.content.AsyncTaskLoader$LoadTask.onPostExecute (AsyncTaskLoader.java:83)
  at androidx.loader.content.ModernAsyncTask.finish (ModernAsyncTask.java:490)
  at androidx.loader.content.ModernAsyncTask$InternalHandler.handleMessage (ModernAsyncTask.java:507)
  at android.os.Handler.dispatchMessage (Handler.java:106)
  at android.os.Looper.loopOnce (Looper.java:201)
  at android.os.Looper.loop (Looper.java:288)
  at android.app.ActivityThread.main (ActivityThread.java:7898)
  at java.lang.reflect.Method.invoke
  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:548)
  at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:936)

Start at AttachmentPresenter.loadAllAvailableAttachments() around line 210 and follow its call from MessageCompose.processDraftMessage(). Reproduce with an encrypted draft and no configured crypto provider, then verify that opening it displays an error message instead of crashing. Check the relevant compose and draft-loading tests, if present, for coverage of this path.