an EL expression applied to a setter of type int automatically coerced a NULL value into a ZERO in ZK 7.
In ZK 8 some int component properties now have an IntegerPropertyAccess wrapping the int value. This affects NULL coercion, leading to NullPointerExceptions when NULL value is attempted to be applied to the real setter, which accepts only int, (and not Integer)

The attachment null-in-el-simple.zul show this problem in a simplified scenario.
The integer property could be dynamic in a more complex scenario.