Deleting an event deletes autogenerated pages and associated subpages

[absempere]

If an event is deleted, any associated autogenerated page is also deleted, and following the deletion pattern, subpages are also deleted. This also crashes the full project in AVA.

Deleting an event with an autogenerated page works. Deleting an event with an autogenerated page with subpages breaks.

There are two ways to approach this depending on time:

1. When a page is deleted, move subpages to the top level.
2. Update the deletion alert to say subpages will be deleted and ask the user to move subpages to the top level prior to deleting an event.

[absempere]

@ajolipa I ran into an issue: I have a project that I haven't published. I created an event with an autogenerated page. Then I made a subpage. I tried to delete the event, and I got the alert saying that this wasn't possible. Perfect.

I went to the Site Builder and moved the Subpage to the top level. I still haven't published the project, but the Site Builder thinks that the autogenerated event page still has a subpage, and I get the alert saying I can't delete the event.

Same thing even when I made Subpage the home page.