java.lang.IllegalArgumentException
        at org.briarproject.briar.sharing.SharingManagerImpl.sendInvitation(SharingManagerImpl.java:241)
        at org.briarproject.briar.android.sharing.ShareForumControllerImpl$1.run(ShareForumControllerImpl.java:71)
        at org.briarproject.briar.android.controller.DbControllerImpl$1.run(DbControllerImpl.java:37)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
        at java.lang.Thread.run(Thread.java:818)

• Android version: 6.0
• Phone model: SUNNY (V2502AN)
• Briar version: 0.16.3 (531e555b)
• User comment: "Crashed when invited."