update c24 language to have 0-valued prefs throw an error
update c24 language to have 0-valued prefs throw an error

gidden/cyclus.github.com,rwcarlsen/cyclus.github.com,gidden/cyclus.github.com,gidden/cyclus.github.com,rwcarlsen/cyclus.github.com,rwcarlsen/cyclus.github.com