Backup Scheduling: Internal server error for scheduled backups after deleting storage location

User Impact:

User can not see any list of scheduled backups and also newly created items after deleting storage location.

Steps to reproduce:

Create Storage Location

Add sheduled backup 

Delete Storage Location

Actual result:

Internal Server Error for List of scheduled backups after deleting Storage Location.

Expected result:

User is warned that storage location can not be deleted. Add Force delete option for Storage Location which already has scheduled backups with notice for user, that all scheduled backups will also be deleted.