Steps to reproduce the issue

(1) Remove Hathor template. (set Isis to default Admin)
(2) Visit Template Manager: Customise Template

Expected result

A page without notifications of non-objects.

Actual result

Notice: Trying to get property of non-object in /usr/local/zend/apache2/htdocs/administrator/components/com_templates/views/template/view.html.php on line 222

Notice: Trying to get property of non-object in /usr/local/zend/apache2/htdocs/administrator/components/com_templates/views/template/view.html.php on line 249

System information (as much as possible)

J3.2.2 Vanilla

Additional comments

222 could be rewritten:
if ($this->hathor && $this->hathor->home == 0)

249 could be rewritten:
if ($this->hathor && $this->hathor->home == 0)

However, it would be best to eliminate the hard dependancy upon a removable template!