defaults.luac = get 'luac',
defaults.prep = get 'prep',
defaults.prepa = get 'prepa',
defaults.prepcache = get 'prepcache',
defaults.luaccache = get 'luaccache',
defaults.suffix = get 'suffix',
defaults.extension = get 'extension',
defaults.naming = get 'naming',--order is important, e=strip extension, s=add suffix, t=replace with target if target exists
defaults.tgt = '',
There shouldn't be commas at the end of each line, as each line here is a separate statement (optionally, you can end it with a semicolon though).
For a code this advanced it's kinda suspicious that you can't read error messages. Presumably this isn't your code?