Fetch failed error trying to edit pages with the latest version of Grav and admin plugin

[Stuart54]

Updated to latest version of Grav and plugins yesterday.

Grav v1.7.49.2 - Admin v1.10.49

Now cannot edit pages. When I try and make any changes and [Save] I get a red error message popup:

Fetch failed
TypeError: Cannot convert undefined or null to object
at Object.keys ()
at http://192.168.1.162/user/plugins/admin/themes/grav/js/admin.min.js?d9a35d309a:3875:16
at http://192.168.1.162/user/plugins/admin/themes/grav/js/admin.min.js?d9a35d309a:831:12

The changes are not saved and the old version of the page reloads.

[rhukster]

I have released an updated admin that hopefully fixes some of this edge case JS errors