1. Set up a group assignment with the following group submission settings:
   Students submit in Groups: YES
   Require group to make Submission: NO
   Require all group members submit: YES
   Grouping for student Groups: None

1. Set the trainer in a separate group
2. If the Trainer enters the assignment the following error will appear (with Debug Information)

You can't add comments

More information about this error

× Debug info:
Error code: nopermissiontocomment

× Stack trace:
line 58 of /mod/assign/submission/comments/lib.php: comment_exception thrown
line ? of unknownfile: call to assignsubmission_comments_comment_validate()
line 7411 of /lib/moodlelib.php: call to call_user_func_array()
line 7393 of /lib/moodlelib.php: call to component_callback()
line 941 of /comment/lib.php: call to plugin_callback()
line 952 of /comment/lib.php: call to comment->validate()
line 440 of /comment/lib.php: call to comment->can_view()
line 74 of /mod/assign/submission/comments/locallib.php: call to comment->output()
line 1146 of /mod/assign/renderer.php: call to assign_submission_comments->view_summary()
line 319 of /lib/outputrenderers.php: call to mod_assign_renderer->render_assign_submission_plugin_submission()
line 901 of /mod/assign/renderer.php: call to plugin_renderer_base->render()
line 319 of /lib/outputrenderers.php: call to mod_assign_renderer->render_assign_submission_status()
line 4579 of /mod/assign/locallib.php: call to plugin_renderer_base->render()
line 4830 of /mod/assign/locallib.php: call to assign->view_student_summary()
line 594 of /mod/assign/locallib.php: call to assign->view_submission_page()
line 52 of /mod/assign/view.php: call to assign->view()

1. The Moodle site doesn't redner the Content properly caus of a missing exception handling.