func TestEndpointResponse_errors_As(t *testing.T) {
	myres := &myResponse{
		E: liberrors.E{
			Code:    400,
			Message: "bad request",
		},
	}
	var err error = myres
	epr := &EndpointRequest{
		Error: err,
	}
	var (
		errIn  *liberrors.E
		errIn2 = &liberrors.E{}
	)
	got := errors.As(epr.Error, &errIn)
	test.Assert(t, "EndpointRequest: errors.As", true, got)
	test.Assert(t, "errors.As with unintialized E:", errIn, &myres.E)
	got = errors.As(epr.Error, &errIn2)
	test.Assert(t, "EndpointRequest: errors.As", true, got)
	test.Assert(t, "errors.As with initialized E:", errIn2, &myres.E)
}
The EndpointResponse when returned as error should be able to converted
to liberrors.E using errors.As().
package http
import (
	"errors"
	"testing"
	liberrors "github.com/shuLhan/share/lib/errors"
	"github.com/shuLhan/share/lib/test"
)
type myResponse EndpointResponse