Fix migration to rollback

db/migrate/20220128044651_remove_annomark_id_in_annotations.rb

@@ -1,5 +1,9 @@
 class RemoveAnnomarkIdInAnnotations < ActiveRecord::Migration[6.1]
-  def change
+  def up
-    safety_assured { remove_column :annotations, :annomark_id, :integer, null: false }
+    safety_assured { remove_column :annotations, :annomark_id, :integer }
+  end
+
+  def down
+    add_column :annotations, :annomark_id, :integer, null: false
   end
 end