Attempting to install `PostCalendar` yields the following error:

```
The 'extensions' module returned an error in 'initialise'.

Did not create default categories (An exception occurred while executing 'INSERT INTO categories_registry (modname, entityname, property, category_id) VALUES (?, ?, ?, ?)' with params {"1":"PostCalendar","2":"CalendarEvent","3":"Main","4":10001}: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'entityname' in 'field list').
```