Gateway: errors messages for net data

[DDorch]

When the file containing net data not exists or is empty, the gateway.log file is filled by this kind of messages:

2019-07-18 04:29:15,322 :: ERROR :: Impossible to get variable C3: list index out of range
2019-07-18 04:29:20,327 :: ERROR :: Impossible to get variable C3: list index out of range
2019-07-18 04:29:25,332 :: ERROR :: Impossible to get variable C3: list index out of range
2019-07-18 04:29:30,337 :: ERROR :: Impossible to get variable C3: list index out of range