Merge pull request #18559 from mvdbeek/dataset_new_check

    def ensure_dataset_on_disk(self, trans, dataset):

        # Not a guarantee data is really present, but excludes a lot of expected cases

        if not dataset.dataset:

            raise exceptions.InternalServerError("Item has no associated dataset.")

        if dataset.purged or dataset.dataset.purged:

            raise exceptions.ItemDeletionException("The dataset you are attempting to view has been purged.")

        elif dataset.deleted and not (trans.user_is_admin or self.is_owner(dataset, trans.get_user())):

            raise exceptions.ItemDeletionException("The dataset you are attempting to view has been deleted.")

        elif dataset.state == Dataset.states.UPLOAD:

            raise exceptions.Conflict("Please wait until this dataset finishes uploading before attempting to view it.")

        elif dataset.state == Dataset.states.NEW:

            raise exceptions.Conflict("The dataset you are attempting to view is new and has no data.")

        elif dataset.state == Dataset.states.DISCARDED:

            raise exceptions.ItemDeletionException("The dataset you are attempting to view has been discarded.")

        elif dataset.state == Dataset.states.DEFERRED: