Padrino で Better Errors を使う ref: http://qiita.com/items/1512c5c4aab5d51c811a

boot.rb

# …
# Load our dependencies
equire 'rubygems' unless defined?(Gem)
require 'bundler/setup'
Bundler.require(:default, PADRINO_ENV)

# ココを追加
if Padrino.env == :development
  Padrino::Application.use BetterErrors::Middleware
  BetterErrors.application_root = PADRINO_ROOT
  BetterErrors.logger = Padrino.logger
  # 表示を許可するアクセス元 IPの指定
  # thanks! @dayflower
  # BetterErrors::Middleware.allow_ip! "127.0.0.0/8" # default
  # BetterErrors::Middleware.allow_ip! "::1/128"     # default
end

##
# ## Enable devel logging
#
# ...

file0.txt

$ ruby -v
ruby 1.9.3p327 (2012-11-10 revision 37606) [x86_64-darwin11.4.2]
$ padrino -v
Padrino v. 0.10.7

file2.txt

$ bundle install

Gemfile

group :development do
  gem "better_errors"
  gem "binding_of_caller"
end