undefined method `add_referer' for nil:NilClass (NoMethodError) ./tdiary/defaultio.rb:92:in `restore_referer' ./tdiary/defaultio.rb:89:in `each' ./tdiary/defaultio.rb:89:in `restore_referer' ./tdiary/defaultio.rb:86:in `each' ./tdiary/defaultio.rb:86:in `restore_referer' ./tdiary/defaultio.rb:84:in `open' ./tdiary/defaultio.rb:84:in `restore_referer' ./tdiary/defaultio.rb:155:in `transaction' ./tdiary.rb:1873:in `initialize' index.rb:52:in `new' index.rb:52