No errors are raised when [common]package value is empty

It seems as though if the `[common]package` field in the `request.cfg` is empty, no errors are raised. This value is used to create distinct directory structured for separate rounds of processing. At the moment, if the value is empty, the directory structure will simply be created without it and no error is raised.

Start with request.cfg and the code path that reads the [common]package value; reproduce processing with an empty value and trace where validation is skipped. Done means an empty value raises an error before the directory structure is created, with coverage for this configuration case.

Written by the indexing model from the issue text.