      def call(exception, locale, key, options)
        if exception.is_a?(MissingTranslation)
          #
          # TODO: this block is to be replaced by `exception.message` when
          # rescue_format is removed
          if options[:rescue_format] == :html
            if @rescue_format_deprecation
              $stderr.puts "[DEPRECATED] I18n's :recue_format option will be removed from a future release. All exception messages will be plain text. If you need the exception handler to return an html format please set or pass a custom exception handler."
              @rescue_format_deprecation = true
            end
            exception.html_message
          else
            exception.message
          end

        elsif exception.is_a?(Exception)
          raise exception
        else
          throw :exception, exception
        end
      end
The software does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.