Objects without custom delta properties can return false for CanSkipUpdate with net.PushModelSkipUndirtiedReplication enabled

This seems to occur after receiving a Nak for certain actors. FObjectReplicator::ReceivedNak will decrement SendingRepState.CustomDeltaChangeIndex even if the object has no custom delta properties. When later comparing the custom delta change indexes in CanSkipUpdate, RepChangelistState.CustomDeltaChangeIndex will be 0 as expected, but SendingRepState.CustomDeltaChangeIndex may be something like 4294967295 (due to decrementing an unsigned int with a value of 0).

Enable push model and net.PushModelSkipUndirtiedReplication. Using network emulation with bad conditions, replicate an actor without any custom delta properties using push-model.
This results in FObjectReplicator::CanSkipUpdate beginning to consistently return false due to RepChangelistState.CustomDeltaChangeIndex not being equal to SendingRepState.CustomDeltaChangeIndex.