Fix overzealous cleanup

app/javascript/src/flash.js

-function flash(kind, message) {
+window.flash = function (kind, message) {
   const allowed_kinds = ['alert-success', 'alert-info', 'alert-warning', 'alert-danger'];
   if (allowed_kinds.indexOf(kind) === -1) {
     console.error(`ASSERT: invalid flash message kind ${kind}`);

app/services/set_quiz_visibility_service.rb

@@ -85,6 +85,8 @@ class SetQuizVisibilityService
     quiz.visible_to_students = vis
 
     if quiz.visible_to_students
+      groups_by_course = DTUAuth2::CachedAuthorizationManager.groups_by_course(quiz.course_id)
+
       eligeable_students = quiz.group_names.map do |group_name|
         groups_by_course[group_name]&.select{ |user| user.acl == 'student'}
       end.compact.flatten