The reason for this is that these are rolling templates and the Qubes
packages cannot keep up with the changes.
Almost certainly, when you were installing the Kali packages you removed
one or more of the qubes packages.
You may be able to access a console using `sudo xl console..` in dom0,
and then see what package was removed, and restore it.
It's always best to put a hold on the qubes packages, and be prepared to
have a broken/inconsistent package system. That and periodically
snapshotting/cloning the template during build process, (and keeping
close eye on what actions will be taken) will help a great deal.
In the present case, you may be able to revert to previous state by
using `qvm-volume revert` in dom0