Lint error from internal packages

[maguro]

I have functions that reside in an internal package that return error. I am getting the "error returned from external package is unwrapped" error even though it's internal. For example:

foo/stats.go:43:10: error returned from external package is unwrapped: sig: func 
acme.com/foo/internal.Bar(ctx context.Context, key string) (ok bool, err error)

[tomarrell]

Is this call through an interface?