unlucky 13 character config name

13-character config names cause an unusual 'can't convert nil into String' error, evidently caused within OptParse.

# Sample::manifest run checks
class Sample < Tap::Task
  config :abcdefghijklm, ""
end

  % tap run -- sample --help

Will raise this error. Adding a comment after config is a workaround. I think this also has to do with the awful presentation of long config names by OptParse.