Use Popup.back() instead of Popup.close() to get no conflicts if a Popup is opened as "Sub Popup"

- .back() is also .close() if there is no "popup layer" left

client/components/users/userAvatar.js

@@ -290,7 +290,7 @@ Template.cardMemberPopup.helpers({
 Template.cardMemberPopup.events({
   'click .js-remove-member'() {
     Cards.findOne(this.cardId).unassignMember(this.userId);
-    Popup.close();
+    Popup.back();
   },
   'click .js-edit-profile': Popup.open('editProfile'),
 });