DSL methods need to check arguments. In particular, Language#data_bag_item

Calling data_bag_item("databag", nil) never checks any arguments, which results in a call to http://chef.example.com/data/databag/, which returns the list of data bags and their URLs. The list of data bag items and their URLs (luckily) is not a valid data bag, so you get an error about the data bag not having an id. We should check the arguments, and also rescue errors and print a useful message in case of error.