Briar had been alive for ~20 hours in the background when I got a notification of three new private group messages. I clicked the notification which lead straight to this NPE:

ava.lang.NullPointerException: Attempt to invoke interface method 'boolean java.util.List.add(java.lang.Object)' on a null object reference at org.briarproject.briar.client.MessageTreeImpl.parseNode(MessageTreeImpl.java:70) at org.briarproject.briar.client.MessageTreeImpl.add(MessageTreeImpl.java:48) at org.briarproject.briar.client.MessageTreeImpl.add(MessageTreeImpl.java:55) at org.briarproject.briar.android.threaded.NestedTreeList.add(NestedTreeList.java:28) at org.briarproject.briar.android.threaded.ThreadItemAdapter.add(ThreadItemAdapter.java:86) at org.briarproject.briar.android.threaded.ThreadListActivity.addItem(ThreadListActivity.java:339) at org.briarproject.briar.android.threaded.ThreadListActivity$5.onResultUi(ThreadListActivity.java:321) at org.briarproject.briar.android.threaded.ThreadListActivity$5.onResultUi(ThreadListActivity.java:318) at org.briarproject.briar.android.controller.handler.UiResultExceptionHandler$1.run(UiResultExceptionHandler.java:24) at org.briarproject.briar.android.activity.BaseActivity$1.run(BaseActivity.java:104) at android.os.Handler.handleCallback(Handler.java:739) at android.os.Handler.dispatchMessage(Handler.java:95)