yhat/ggplot — pull request #258 by cosinequanon (2014-03-28 03:33:53+00:00)
Title: Add checks to chart components on init.

Check for components that should never be None and check for components that should be of a numeric type. I figure it makes more sense to throw the error early. This is in response to https://github.com/yhat/ggplot/issues/255