Fix for go-1.18, Errorf doesn't accept verb %w

[dbudworth]

https://pkg.go.dev/fmt#Errorf

%w not accepted in 1.18?
https://go.dev/play/p/KztaAZ-xjmT indicates it does, what was the problem you ran in to?

[mikelolasagasti]

The error I get is:

./testping.go:102:5: (*testing.common).Errorf does not support error-wrapping directive %w

[dbudworth]

oops, my mistake. For some reason I read this as fmt.Errorf, not t.Errorf