message: Prevent crashing notification panel when threads have no messages
diff: @@ -50,6 +50,10 @@ export default Service.extend({
  }
  let priority = thread.get('priority');
  + if (!priority) {
  + return groupedThreads;
  + }
  +
  let priorityId = priority.get('id');
  if (!groupedThreads[priorityId]) {
  groupedThreads[priorityId] = {
  