500 Internal Server Error

undefined method `<' for nil:NilClass (NoMethodError)

/virtual/mizuki/public_html/diary/tdiary/core_ext.rb:103:in `safe'
/virtual/mizuki/public_html/diary/tdiary/config.rb:215:in `load_cgi_conf'
(tdiary.conf):344:in `configure_attrs'
/virtual/mizuki/public_html/diary/tdiary/config.rb:120:in `eval'
/virtual/mizuki/public_html/diary/tdiary/config.rb:120:in `configure_attrs'
/virtual/mizuki/public_html/diary/tdiary/config.rb:12:in `initialize'
/virtual/mizuki/public_html/diary/tdiary/dispatcher/index_main.rb:14:in `new'
/virtual/mizuki/public_html/diary/tdiary/dispatcher/index_main.rb:14:in `initialize'
/virtual/mizuki/public_html/diary/tdiary/dispatcher/index_main.rb:6:in `new'
/virtual/mizuki/public_html/diary/tdiary/dispatcher/index_main.rb:6:in `run'
/virtual/mizuki/public_html/diary/tdiary/dispatcher.rb:21:in `dispatch_cgi'
index.rb:31:in `<main>'