[Glitch] Add missing null handling in notification reducer

Port 2f3ac14a43 to glitch-soc

app/javascript/flavours/glitch/reducers/notifications.js

@@ -92,7 +92,7 @@ const expandNormalizedNotifications = (state, notifications, next) => {
 };
 
 const filterNotifications = (state, relationship) => {
-  return state.update('items', list => list.filterNot(item => item.get('account') === relationship.id));
+  return state.update('items', list => list.filterNot(item => item !== null && item.get('account') === relationship.id));
 };
 
 const updateTop = (state, top) => {
@@ -104,7 +104,7 @@ const updateTop = (state, top) => {
 };
 
 const deleteByStatus = (state, statusId) => {
-  return state.update('items', list => list.filterNot(item => item.get('status') === statusId));
+  return state.update('items', list => list.filterNot(item => item !== null && item.get('status') === statusId));
 };
 
 const markForDelete = (state, notificationId, yes) => {