Gnome-Settings allows setting background to something Phosh cannot handle

What application is this relating to?

Gnome Settings and Phosh

What problem did you encounter

Using Settings, I tried to set one of the proposed background, which makes Phosh display a blank background instead.

Failed to load background: couldn’t reckognize the image file format for “/usr/share/desktop-base/software-theme/wallpaper/gnome-background.xml”

What is the actual behaviour?

see above

What is the expected behaviour?

Either setting the background work, or the background isn't suggested by Settings.

How to reproduce

Please provide steps to reproduce the issue. If it's a graphical issue please attach screenshots.

Which version did you encounter the bug in?

I used the system's repositry, after apt update && apt upgrade. Version of the packages:

gnome-settings 3.30.2-3, architecture amd64
phosh 0.0.5~829.gbp0ffcff, architecture amd64

What hardware are you running on?

Running on the amd64 qemu image

Relevant logfiles

Nothing in journalctl apart from phosh: Failed to load background: couldn’t recognize the image file format for “/usr/share/desktop-base/softwaves-theme/wallpaper/gnome-background.xml” appearing thrice.