I couldn't update as the new pacman broke yay. So I removed yay and updated with pacman -Syu. Then pakku did not work. So I got the yay PKGBUILD and built and installed it with makepkg -sirc. Then yay -Syu updated pakku (actually pakku-git) which now works too.
However, while doing this I read in the yay aur comments they had some suggestions for even easier workarounds.
https://aur.archlinux.org/packages/yay/ (https://aur.archlinux.org/packages/yay/)
Having used these 2 AUR helpers for a bit, yay is very good and I'd recommend it, pakku has some extra features which could be useful but is a bit unfinished perhaps in places, although it generally works fine, however yay is better overall at present I think. They both add a lot of functionality over just pacman though, and are very useful and save a lot of time.