Deleting an item displayed in Content Scheduler makes Dashboard unavailable.

Steps to reproduce:
1. Login as admin
2. Create new Folder (named "Test")
3. Create new Landing Page
4. Add Content Scheduler block
5. Add the item created in step 2 to the block
6. Publish the Landing Page
7. Go to Content -> Content Structure
8. Send the Folder created in step 2 to trash

Expected:
Item is deleted. Content Scheduler handles the lack of item (does not display it).

Actual:
Error about missing location item is displayed. It's not possible to open the Dashboard.