Apply automatic rubocop fixes

db/migrate/20181129093207_drop_errors.rb

@@ -1,5 +1,6 @@
-class DropErrors < ActiveRecord::Migration[5.2]
+# frozen_string_literal: true
 
+class DropErrors < ActiveRecord::Migration[5.2]
   # define old CodeOcean::Error module so that the migration works
   module CodeOcean
     class Error < ApplicationRecord
@@ -15,21 +16,16 @@ class DropErrors < ActiveRecord::Migration[5.2]
         true
       end
 
-      def to_s
-        id.to_s
-      end
+      delegate :to_s, to: :id
     end
   end
 
-
-
   def change
-
     puts 'Migrating CodeOcean::Errors to StructuredErrors using RegEx. This might take a (long) while but will return.'
     submissions_controller = SubmissionsController.new
 
     # Iterate only over those Errors containing a message and submission_id
-    CodeOcean::Error.where.not(message: [nil, ""]).where.not(submission_id: [nil, ""]).each do |error|
+    CodeOcean::Error.where.not(message: [nil, '']).where.not(submission_id: [nil, '']).each do |error|
       raw_output = error.message
       submission = Submission.find_by(id: error.submission_id)