It is possible to insert a non-existing Template to a Permission Scheme

It is possible to insert a non-existing Template to a Permission Scheme.
Steps to reproduce:

• Open the templates page.
• In another tab, open the Permission Schemes page and edit the permissions of a scheme.
• Press Assign Templates button (Global or any Issue type)
• In the templates tab delete a template.
• In the Permissions tab add the deleted template.