If the user who created a site has been deleted, but in this site there is a calendar, the rest of users can't access to Notification Templates.
Steps to reproduce:
1.- User A creates a site called, i.e., SiteUserA.
2.- User A is deleted.
3.- User B add a calendar in SiteUserA.
4.- User B, or any user who can view the calendar, try to check 'Current Site Calendar --> Select any Calendar --> Calendar Settings --> Notification Templates'.
Notification template is shown.
NoSuchUserException is thrown and error is shown