500 Internal Server Error

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

/public/pub7/home7/oct/html/chaos/tdiary/defaultio.rb:42:in `block in restore_comment'
/public/pub7/home7/oct/html/chaos/tdiary/defaultio.rb:39:in `open'
/public/pub7/home7/oct/html/chaos/tdiary/defaultio.rb:39:in `restore_comment'
/public/pub7/home7/oct/html/chaos/tdiary/defaultio.rb:167:in `transaction'
/public/pub7/home7/oct/html/chaos/tdiary.rb:1953:in `initialize'
index.rb:59:in `new'
index.rb:59:in `<main>'