UI "Images" page fails to render when images exist that have empty properties.

[tjwsl]

In 5.20-f3dd836 (rev 27049), if there are images present that lack content in the 'properties' attribute:

$ lxc image show opnsense-23.7
auto_update: false
properties: {}
public: false
expires_at: 0001-01-01T00:00:00Z
profiles:
- default

then the "Images" menu item in the UI fails to render properly. See attached screenshot.