Hi @bardmorgan_7142 ,
That error seems to be a UI-related error with the Build Script Template editor. Basically that __ahempty value is meant to trigger a validation warning to force you to pick a package source.
When you edit the build script, what do you have set for the package source drop-downs? It should be a ProGet feed, at least for publishing. But it's not required.
Also, if you "Edit As OtterScript", you should be able to see where the __ahempty is being added to the script, and hopefully fix. Seeing taht would help us debug it :)
Cheers,
Alana