[senechome] Avoid null pointer errors (#12512)

[senechome] Avoid null pointer errors (#12512)

Looks like the new generation of SenecIES power storage systems, which are using LiPo technology, provide additional data in the JSON array.
This data is not available in the old generation, which lead to missing data, when asking for a key and in further null pointer exceptions when going deeper in the data structure.

Therefore making a trivial check to detect the new generation of devices and skip the troubling section entirely.
CON: The section of items would not be updated. A to-do is of course to split the old and new generation into separate models of devices.

Fixes #11606

Also-By: Erwin Guib <eguib@web.de>
Also-By: Korbinian Probst <kp.droid.dev@gmail.com>
Signed-off-by: Thomas Karl Pietrowski <thopiekar@gmail.com>