Fix undefined class property access after upgrade from 19 to 20

Fix undefined class property access after upgrade from 19 to 20

The serialized data in 19 has one property less and this was not
considered in the code. Hence adding a fallback. Moreover I'm changing
the deserialization into an array instead of object, as that is the
safer option.

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>