[28315] Only attach attachments to PDF if any exists

If the work package has attachments that are not exportable, the empty
table cell would result in an  error otherwise

https://community.openproject.com/wp/28315

[ci skip]

app/assets/stylesheets/content/_action_menu_main.sass

@@ -30,7 +30,7 @@
   ul
     list-style-type: none
     margin: 0
-    width: 230px
+    width: 240px
     border: 1px solid #dddddd
     box-shadow: 1px 1px 4px rgba(0, 0, 0, 0.15)
     padding: 3px 0

app/assets/stylesheets/content/_modal.sass

@@ -150,12 +150,14 @@ ul.export-options
     margin: 0 0 30px 0
     text-align: center
     display: inline-block
-    min-width: 32%
+    width: 32%
     a
       cursor: pointer
       text-decoration: none
       color: $body-font-color
       font-weight: normal
+      overflow-wrap: break-word
+      word-wrap: break-word
       &:hover, &:active
         text-decoration: none
         color: $body-font-color

app/models/work_package/pdf_export/work_package_list_to_pdf.rb

@@ -151,9 +151,11 @@ class WorkPackage::PdfExport::WorkPackageListToPdf < WorkPackage::Exporter::Base
       if options[:show_attachments] && work_package.attachments.exists?
         attachments = make_attachments_cells(work_package.attachments)
 
-        result << [
-          { content: pdf.make_table([attachments]), colspan: description_colspan }
-        ]
+        if attachments.any?
+          result << [
+            { content: pdf.make_table([attachments]), colspan: description_colspan }
+          ]
+        end
       end
 
       if query.grouped? && (group = query.group_by_column.value(work_package)) != previous_group