This error is the same as what I mention in my previous post. You are using the spread command with the PRODUCT_SUB_LINE_DESCR and returns columns as your key and fill arguments, respectively. This will remove these columns from the dataset as the dataset has been transformed. You can not use either of them in your ggplot functions (since they are no longer in your dataset) unless you use gather to return them.
Also, it is discouraged to @name reference a user who has not engaged in a thread on their own. Please see the community faq about @name usage