500 Internal Server Error

undefined method `[]' for nil:NilClass (NoMethodError)

./tdiary/io/default.rb:93:in `restore_referer'
./tdiary/io/default.rb:92:in `each'
./tdiary/io/default.rb:92:in `restore_referer'
./tdiary/io/default.rb:79:in `open'
./tdiary/io/default.rb:79:in `restore_referer'
./tdiary/io/default.rb:189:in `transaction'
./tdiary.rb:957:in `initialize'
./tdiary/dispatcher/index_main.rb:108:in `new'
./tdiary/dispatcher/index_main.rb:108:in `create_tdiary'
./tdiary/dispatcher/index_main.rb:21:in `run'
./tdiary/dispatcher/index_main.rb:6:in `run'
./tdiary/dispatcher.rb:21:in `dispatch_cgi'
index.rb:36