I'd like to propose the idea of using github.com/pkg/errors for errors.
Logging regular errors and panic errors could give us proper stack traces which makes debugging / fixing problems much easier because you can see from where the error has been returned.
I have already applied this on our fork (see https://travis-ci.org/qdentity/graphql-go) and all tests pass.
I'm happy to create a PR if this idea is also useful for this repo.