Hiki Error

uninitialized constant Hiki::Util::Diff (NameError)
/usr/share/hiki/hiki/util.rb:217:in `unified_diff'
/usr/share/hiki/hiki/command.rb:375:in `rescue in cmd_diff'
/usr/share/hiki/hiki/command.rb:370:in `cmd_diff'
/usr/share/hiki/hiki/command.rb:130:in `block in dispatch'
/usr/lib/ruby/2.7.0/timeout.rb:95:in `block in timeout'
/usr/lib/ruby/2.7.0/timeout.rb:33:in `block in catch'
/usr/lib/ruby/2.7.0/timeout.rb:33:in `catch'
/usr/lib/ruby/2.7.0/timeout.rb:33:in `catch'
/usr/lib/ruby/2.7.0/timeout.rb:110:in `timeout'
/usr/share/hiki/hiki/command.rb:103:in `dispatch'
/usr/share/hiki/hiki.cgi:40:in `block in <top (required)>'
/usr/share/hiki/hiki/storage.rb:14:in `open_db'
/usr/share/hiki/hiki.cgi:38:in `<top (required)>'
/home/taki/public_html/tewasura/hiki.cgi:2:in `load'
/home/taki/public_html/tewasura/hiki.cgi:2:in `<main>'