The jar command (jar xf, Java Archive eXtract File) in line 27 in pkgbuild isn't part of the openjdks, therefore building there falls
How to reproduce: archlinux-java java-10-openjdk #(assuming you have it installed) pacman -S weka
How to fix: Use zip or tar utility, that also supports parameter xf instead or just ship the icon via wget (would get rid of gif2png)
Pinned Comments
jonathon commented on 2020-06-03 10:58 (UTC) (edited on 2020-06-03 10:59 (UTC) by jonathon)
Please be aware that "odd-numbered" releases are development releases. Please do not flag this package "out of date" because there is a new development release.
"Weka 3.8 is the latest stable version and Weka 3.9 is the development version." [1]