Add an exception to be raised if a table is empty

[AnastasiaProkaieva]

Problem:
Currently, if a dataset is empty(table contains no records), there will be an error through not found num_workers, while I would expect to get an error: your table is empty please verify your path is correct or please use the table that contains records.

Proposed Solution:
Do a count of records on a table and add an exception with a proper message.

Can fix it.