People download this by accident and then their game crashes.

Seems like you just delete these two lines:

        addArtifact sourcesJar
        additionalArtifacts.forEach { artifact -> artifact.displayName = "$project.project_name v$project.mod_version for $project.minecraft_version"}

However the existing sources jars on CurseForge need to be removed as well using the "Archive" button.

I approve, I'm gonna need an intellectual to dive into the gradle depths however :P

Aight seems simple enough