That's right but you are not returning the error. Here is the corrected snippet https://play.golang.org/p/A3YRSTg-7K https://play.golang.org/p/A3YRSTg-7K Edit:

That's right but you are not returning the error. Here is the corrected snippet https://play.golang.org/p/A3YRSTg-7K https://play.golang.org/p/A3YRSTg-7K Edit: your example works too, though I find it weird...