[non-functional] Monkey patch exception logging into async_sinatra (quick workaround)

async_sinatra_error_patch.rb

# Monkey patch exception logging into async_sinatra
#
# This is a workaround for the lack of error handling/logging on asynchronous
# requests (e.g. aget, apost) when using async_sinatra 0.5.0, sinatra 1.2.6,
# thin 1.2.11, and rack 1.3.0.
#
# See http://stackoverflow.com/questions/6427033/how-do-i-log-asynchronous-thinsinatrarack-requests
module Sinatra::Async
        alias :oldaroute :aroute

        def aroute *args, &block
                oldaroute(*args) { |*a|
                        begin
                                block.call *a
                        rescue Exception => e
                                status 500
                                puts "Asynchronous exception:"
                                puts "#{e.class} - #{e.message}: \n #{e.backtrace.join("\n ")}\n"
                                ahalt e
                        end
                }
        end
end

This doesn't work because the execution context of the block is changed, preventing access to methods like content_type and status. Some metaprogramming would be required to bind the block call to the right context, as is done in the async_sinatra code.