yardoc issue 300 workaround

yardoc.rb

      # Parses commandline arguments
      # @param [Array<String>] args the list of arguments
      # @return [Boolean] whether or not arguments are valid
      # @since 0.5.6
      def parse_arguments(*args)
        options[:markup] = nil # reset markup
        
        # Hack: parse out --no-yardopts, --no-document before parsing files
        ['document', 'yardopts'].each do |file|
          without, with = args.index("--no-#{file}") || -2, args.index("--#{file}") || -1
          send("use_#{file}_file=", false) if without > with
        end

        # Parse files and then command line arguments
        optparse(*support_rdoc_document_file!) if use_document_file
        optparse(*yardopts) if use_yardopts_file
        optparse(*args)

        # Last minute modifications
        self.files = ['lib/**/*.rb', 'ext/**/*.c'] if self.files.empty?
        self.files.delete_if {|x| x =~ /\A\s*\Z/ } # remove empty ones
        options[:readme] ||= Dir.glob('README*').first
        if options[:onefile]
          options[:files] << options[:readme] if options[:readme]
          options[:readme] = Dir.glob(files.first).first 
        end
        Tags::Library.visible_tags -= hidden_tags
        add_visibility_verifier
        
        verified_markup_result = verify_markup_options
        
        if generate && !verified_markup_result
          false
        else
          true
        end
      end

Line 30 will store the result of the verify_markup_options and then use that in the comparison below, instead of failing fast when the generate option returns false (when the -n option is used).