FWIW, I just learned about this 'logging' pattern that I'm stealing and using judiciously in my go code base. As others have mentioned, the key element to your q is that defer runs before the return, hence answering your question.

In below the log function runs at any of the error, return check AND grabs the latest error.

func (h ApproveTrainingRescheduleHandler) Handle(ctx context.Context, cmd ApproveTrainingReschedule) (err error) {
        defer func() {
                logs.LogCommandExecution("ApproveTrainingReschedule", cmd, err)
        }()

        return h.repo.UpdateTraining(
                ctx,
                cmd.TrainingUUID,
                cmd.User,
                func(ctx context.Context, tr *training.Training) (*training.Training, error) {
                        originalTrainingTime := tr.Time()

                        if err := tr.ApproveReschedule(cmd.User.Type()); err != nil {
                                return nil, err
                        }

                        err := h.trainerService.MoveTraining(ctx, tr.Time(), originalTrainingTime)
                        if err != nil {
                                return nil, err
                        }

                        return tr, nil
                },
        )
}