class Sinatra::Base

def error(*codes, &block)

handled.
class, or an HTTP status code to specify which errors should be
Define a custom error handler. Optionally takes either an Exception 
def error(*codes, &block)
  args  = compile! "ERROR", //, block
  codes = codes.map { |c| Array(c) }.flatten
  codes << Exception if codes.empty?
  codes.each { |c| @errors[c] = args }
end