diff --git a/lib/shared/mention-utils.js b/lib/shared/mention-utils.js
--- a/lib/shared/mention-utils.js
+++ b/lib/shared/mention-utils.js
@@ -1,7 +1,5 @@
 // @flow
 
-import invariant from 'invariant';
-
 import { oldValidUsernameRegexString } from './account-utils.js';
 import SearchIndex from './search-index.js';
 import { threadOtherMembers } from './thread-utils.js';
@@ -102,8 +100,13 @@
   if (threadInfo.type !== threadTypes.SIDEBAR) {
     return threadInfo.members;
   }
-  invariant(parentThreadInfo, 'sidebars should have parents');
-  return parentThreadInfo.members;
+  if (parentThreadInfo) {
+    return parentThreadInfo.members;
+  }
+  // This scenario should not occur unless the user logs out while looking at a
+  // sidebar. In that scenario, the Redux store may be cleared before ReactNav
+  // finishes transitioning away from the previous screen
+  return [];
 }
 
 export {