can't delete a subject that is in a group of subjects

[julien-louis]

When deleting a subject that is in a group of subjects

"could not execute statement [Cannot delete or update a parent row: a foreign key constraint fails (studies.subject_group_of_subjects, CONSTRAINT FKbuuj437rygsa1u24tfbwicxnh FOREIGN KEY (subject_id) REFERENCES subject (id))] [delete from subject where id=?]; SQL [delete from subject where id=?]; constraint [null]"

May not be a priority though