chore: fix minor cops

Author: macite

app/models/unit.rb

@@ -2254,7 +2254,7 @@ def update_task_status_from_csv(user, csv_str, success, _ignored, errors)
 
     # read data from CSV
     CSV.parse(csv_str, headers: true, return_headers: true,
-                       header_converters: [->(body) { body&.encode('UTF-8', 'binary', invalid: :replace, undef: :replace, replace: '').downcase }],
+                       header_converters: [->(body) { body&.encode('UTF-8', 'binary', invalid: :replace, undef: :replace, replace: '')&.downcase }],
                        converters: [->(body) { body&.encode('UTF-8', 'binary', invalid: :replace, undef: :replace, replace: '') }]).each do |task_entry|
       group = nil
 

test/models/unit_model_test.rb

@@ -405,7 +405,7 @@ def check_task_completion_csv unit, col_count = nil
     CSV.parse(csv_str,
               headers: true,
               return_headers: false,
-              header_converters: [->(body) { body&.encode('UTF-8', 'binary', invalid: :replace, undef: :replace, replace: '').downcase }],
+              header_converters: [->(body) { body&.encode('UTF-8', 'binary', invalid: :replace, undef: :replace, replace: '')&.downcase }],
               converters: [->(body) { body&.encode('UTF-8', 'binary', invalid: :replace, undef: :replace, replace: '') }]).each do |entry|
 
       assert_equal(col_count, entry.length, entry.inspect) unless col_count.nil?
@@ -493,7 +493,7 @@ def test_export_users
     rows = 0
     CSV.parse(csv_str,
               headers: true, return_headers: false,
-              header_converters: [->(body) { body&.encode('UTF-8', 'binary', invalid: :replace, undef: :replace, replace: '').downcase }],
+              header_converters: [->(body) { body&.encode('UTF-8', 'binary', invalid: :replace, undef: :replace, replace: '')&.downcase }],
               converters: [->(body) { body&.encode('UTF-8', 'binary', invalid: :replace, undef: :replace, replace: '') }]).each do |entry|
       assert_json_limit_keys_to_exactly %w[unit_code campus username student_id preferred_name first_name last_name email tutorial], entry.to_hash
       assert_equal 9, entry.count, entry