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.
The Browser Security Handbook is a free and no-nonsense guide to the security concepts in today’s main browsers. It covers all security features, explains why and in which browsers certain attack methods work and talks about experimental security mechanisms in browsers. It’s a recommended read for everyone who creates web applications.
Important read, i remember reading a similar article a few years back (FF1 vs. IE6) and i learned some good stuff.
Get it here
You're seeing this error because I think it is funny.