No, this is not a real Sinatra error :).
This is the personal homepage of Elad Meidar, a web developer and an entrepreneur specializing in Ruby on Rails. I hang around in Israel, and i am currently having the best time of my life over at Fiverr.com
I am a proud member of RailsBridge, Helping new Rails developers get into our world and also contributed a few Patches to the Ruby on Rails core.
rewrite engine is pretty cool, it allows you handle the user’s request and preform actions (redirect, block…) according to a pattern given as parameter.
This main use for rewrites i guess, is to enable pretty URL outside your app, or to support legacy conventions. (Like i should have done here when i moved to mephisto).
You're seeing this error because I think it is funny.