I've had the same "package is broken" error several times in the past.
This week, I got that error, and after restarting computer, still got it for a full day.
I could not repair the Avast installation.
The solution for me was to uninstall Avast free and re-download and re-install it.
I've had to do this before, but not every time I got the "package is broken" error...so it's worth waiting a day, restarting, or repairing before reinstalling.