Ups :-)
It is a little bit embarrassing, but software bugs can also happen to me. Bugs in web applications can lead to something like that showing up in search engine results:
That error message was caused by an flaw on how I handled the
input from the HTTP Accept-Language line, if it was missing my code run into the above error.
So, that example proves one thing - it is very hard to review and audit your own code for flaws and security holes.