Delete event test

The problem is that here you are calling `click_confirm_delete_event_button` on `edit_event_page` and storing the result of that operation in `events_page`, but `click_confirm_delete_event_button` doesn't return anything, so now `events_page` is `None`, instead of the page object you are expecting. 

This can be fixed by returning the page object you expect from the `click_confirm_delete_event_button` method. I will add another comment to that file.