When a glossary entry is created in category and this entry is then deleted, a row in `glossary_entries_categories` (presence of this deleted entry in a category) remains there and is not deleted.
Steps to reproduce:

1. create glossary in any course (with "Appearance" set to "Full with autor" to use categories)
2. create category A
3. create entry B in category A
4. delete entry B
5. try to delete category A - there will be a note, that category contains 1 entry
6. in `glossary_entries_categories` there still will be a row whic points to the deleted entry