Add a db_checker(file.db) [Job_data backup not triggered]
I'm opening this issue regarding the job_data problem related to the experiment a4dd where the job_data.db had no data and made the experiment crash at the end of the run.
The idea is to provide a better output message and load the last backup, avoiding the AS crash.
Also, we could implement a db_checker(path_to_db.db) function or some like that to do this kind of check during the main_loop to avoid metadata losses due to the filesystem. FYI: @mcastril