dgrijalva/jwt-go — pull request #12 by hermanjunge (2014-03-12 07:50:57+00:00)
Title: Update README.md

You cannot perform the not (`!`) operator on an `error`. It gives you `invalid operation: ! error`.

Tested in Go Playground: http://play.golang.org/p/jhlsHoS_gc
and locally on go1.2