Feat/none error date
In case of an error while retrieving offset constant from the DB, the injection date would be equal to the creation time.
The metadata was changed to None in that case beside the empty constant.
One of the drawback of this solution is not tracing if there was no device at all or there might be a constant in the DB and it is just a connection error.
Another solution was to output a string ("00:00:00") of an empty date but then all of the notebooks which uses get_from_db has to be edited with a condition of a string output not only None.
Edited by Karim Ahmed