It isn't common, and the code example wouldn't even compile because "err" is assigned but never used. I imagine that they included the "err" variables to show that they're available, but didn't want to clutter the example with error checks.

You can ignore error codes in go by assigning them to the special variable "_", but, outside of very short toy examples, it is a huge warning sign for terrible code. It's certainly not common to ignore errors in Go.