fixed problem that no new files could be added to an exercise

app/assets/javascripts/exercises.js.erb

@@ -228,7 +228,8 @@ $(function() {
   }
 
   if ($.isController('exercises')) {
-    if ($('table').isPresent()) {
+      // ignore tags table since it is in the dom before other tables
+    if ($('table:not(#tags-table)').isPresent()) {
       enableBatchUpdate();
     } else if ($('.edit_exercise, .new_exercise').isPresent()) {
       execution_environments = $('form').data('execution-environments');

app/views/exercises/_form.html.slim

@@ -40,7 +40,7 @@
     = f.number_field "expected_worktime_minutes", value: @exercise.expected_worktime_seconds / 60, in: 1..1000, step: 1
   h2 Tags
   .table-responsive
-    table.table
+    table.table#tags-table
       thead
         tr
           th = t('activerecord.attributes.exercise.selection')