Updated null-check for value_prop limits types that can be in value. #3555
Description
@abrahamwolk, there's another follow-up problem with #3522, #3474.
We used to have
final Object value = value_prop.getValue();
You changed that into
final VType value = value_prop.getValue();
We have scripts that set local PVs to arrays etc., so their type is for example "PyList" and now we get this cast exception:
WARNING [org.csstudio.display.builder.model] Property update error for 'connected' = true
java.lang.ClassCastException: class org.python.core.PyList cannot be cast to class org.epics.vtype.VType
at org.csstudio.display.builder.representation.javafx.widgets.RegionBaseRepresentation.connectionOrValueChanged(RegionBaseRepresentation.java:264)