Update personal_books_controller.rb

add rescue

app/controllers/personal_books_controller.rb

@@ -76,7 +76,7 @@ class PersonalBooksController < ApplicationController
         when "language"
           t << {"value" => (!book.language.nil? ? t("#{book.language}") : "")}
         else
-          t << {"value" => book.send(fs)}
+          t << {"value" => (book.send(fs) rescue "")}
         end
       end
       book_list << {"books" => t}