previously an error was shown if a series was tried to be deleted that had no files (artefact of the DropZone when many files are uploaded at once). now a messaged is flashed to the user that no files were found and (empty) series is deleted from the db table.
previously if a report was deleted from an archived series, then series existed in the db but not shown in the workbench table. Now when a report is deleted, the corresponding series is updated to reflect that it has no reports and to not be archived (ie be displayed on the Workbench).
fixes: