Best error handling

[tyx]

When an ETL operation throws an exception, it should not interrupt all stuff but only the message concerned.

[tyx]

Attention !!!!

Dans les extractors si on attrape les exceptions, le count ne sera pas fait ! On rentre alors dans une boucle infini !

Il faut mettre un statut sur les message "terminated" qu'on ne propagera pas.

[tyx]

We should introduced 2 types of exception.

First one, as described in first msg to not interrupt process.
Second one, to interrupt the process with a kind message.