Reinstate deleted validation

lib/quby/compiler/entities/outcome_table.rb

@@ -12,6 +12,7 @@ module Quby
         include ActiveModel::Model
         attr_accessor :score_keys, :subscore_keys, :name, :default_collapsed, :questionnaire, :key
 
+        validates :score_keys, :subscore_keys, :questionnaire, :key, presence: true
         validates :name, presence: true, if: proc { |table| table.default_collapsed }
         validate :references_existing_score_keys
         validate :no_outcome_tables_defined_in_score_schemas