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.
source Ruby Inside
Benchmarks say it’s twice as fast as 1.8.7, but developers worn not to use it as a production ruby rght away becouse it may a lot of libraries and Gems.
so, be worned.
You're seeing this error because I think it is funny.