NoMethodError in Percentage_statistics#update
Showing app/views/percentage_statistics/edit.html.erb where line #7 raised:
You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.map
error in percentage_statistics_controller.rb:80:in `update'
This is definitely one of the tougher errors, when something is invalid in a model you can hunt forever in the controller and not find it!