Disable sorttable on tables without rows

Otherwise, the first element of the table body is being fetched which might result in an error for empty tables.

Fixes CODEOCEAN-JZ

app/views/error_template_attributes/index.html.slim

@@ -1,7 +1,7 @@
 h1 = ErrorTemplateAttribute.model_name.human(count: 2)
 
 .table-responsive
-  table.sortable.table
+  table.table class="#{@error_template_attributes.present? ? 'sortable' : ''}"
     thead
       tr
         th

app/views/error_templates/index.html.slim

@@ -1,7 +1,7 @@
 h1 = ErrorTemplate.model_name.human(count: 2)
 
 .table-responsive
-  table.sortable.table
+  table.table class="#{@error_templates.present? ? 'sortable' : ''}"
     thead
       tr
         th = t('activerecord.attributes.error_template.name')

app/views/error_templates/show.html.slim

@@ -13,7 +13,7 @@ h2.mt-4
   = t 'error_templates.attributes'
 
 .table-responsive
-  table.sortable.table
+  table.table class="#{@error_templates.error_template_attributes.present? ? 'sortable' : ''}"
     thead
       tr
         th

app/views/execution_environments/statistics.html.slim

@@ -1,7 +1,7 @@
 h1 = @execution_environment
 
 .table-responsive
-  table.table.table-striped.sortable
+  table.table.table-striped class="#{@execution_environment.present? ? 'sortable' : ''}"
     thead
       tr
         - ['.exercise', '.users', '.score', '.maximum_score', '.stddev_score', '.percentage_correct', '.runs', '.worktime', '.stddev_worktime'].each do |title|

app/views/exercise_collections/statistics.html.slim

@@ -28,7 +28,7 @@ h1 = @exercise_collection
 
 h4.mt-4 = t('activerecord.attributes.exercise_collections.exercises')
 .table-responsive#exercise-list
-  table.table.sortable
+  table.table class="#{@exercise_collection.items.present? ? 'sortable' : ''}"
     thead
       tr
         th = '#'

app/views/exercises/statistics.html.slim

@@ -61,8 +61,9 @@ h1 = @exercise
   - if !policy(@exercise).detailed_statistics?
     - submissions = submissions.final
   - if submissions.any?
+    - users = symbol.to_s.classify.constantize.where(id: submissions.joins(symbol).group(:user_id).select(:user_id).distinct)
     .table-responsive
-      table.table.table-striped.sortable
+      table.table.table-striped class="#{users.present? ? 'sortable' : ''}"
         thead
           tr
             th.header = t('.user')
@@ -71,7 +72,6 @@ h1 = @exercise
             th.header = t('.runs') if policy(@exercise).detailed_statistics?
             th.header = t('.worktime') if policy(@exercise).detailed_statistics?
         tbody
-          - users = symbol.to_s.classify.constantize.where(id: submissions.joins(symbol).group(:user_id).select(:user_id).distinct)
           - users.each do |user|
             - if user_statistics[user.class.name][user.id] then us = user_statistics[user.class.name][user.id] else us = {"maximum_score" => nil, "runs" => nil}
             - label = "#{user.displayname}"

app/views/external_users/statistics.html.slim

@@ -7,7 +7,7 @@ h1 = t('.title')
 
 - if submissions.any?
   .table-responsive
-    table.table.table-striped.sortable
+    table.table.table-striped class="#{exercises.present? ? 'sortable' : ''}"
       thead
         tr
           th.header = t('.exercise')

app/views/request_for_comments/index.html.slim

@@ -17,7 +17,7 @@ h1 = RequestForComment.model_name.human(count: 2)
                   { class: 'form-control', multiple: true, "data-placeholder": t('request_for_comments.index.study_groups.placeholder') })
 
 .table-responsive
-  table.table.sortable.mt-4
+  table.table.mt-4 class="#{@request_for_comments.present? ? 'sortable' : ''}"
     thead
       tr
         th

app/views/study_groups/_form.html.slim

@@ -6,7 +6,7 @@
 
   h3 = t('activerecord.attributes.study_group.members')
   .table-responsive
-    table.sortable.table
+    table.table class="#{@members.present? ? 'sortable' : ''}"
       thead
         tr
           th = t('activerecord.attributes.exercise.selection')

app/views/study_groups/show.html.slim

@@ -12,7 +12,7 @@ h1
 
 h2.mt-4 = t('activerecord.attributes.study_group.members')
 .table-responsive
-  table.sortable.table
+  table.table class="#{@study_group.users.present? ? 'sortable' : ''}"
     thead
       tr
         th =  t('navigation.sections.users')

app/views/tips/index.html.slim

@@ -1,7 +1,7 @@
 h1 = Tip.model_name.human(count: 2)
 
 .table-responsive
-  table.sortable.table
+  table.table class="#{@tips.present? ? 'sortable' : ''}"
     thead
       tr
         th = t('activerecord.attributes.tip.title')