Update uatypes.py

asyncua/ua/uatypes.py

@@ -750,7 +750,10 @@ class Variant(FrozenClass):
         if self.VariantType is None:
             self.VariantType = self._guess_type(self.Value)
         if self.Value is None and not self.is_array and self.VariantType not in (VariantType.Null, VariantType.String, VariantType.DateTime, VariantType.ExtensionObject):
-            raise UaError(f"Non array Variant of type {self.VariantType} cannot have value None")
+            if self.Value == None and self.VariantType == VariantType.NodeId:
+                self.Value = NodeId(0,0)
+            else:
+                raise UaError(f"Non array Variant of type {self.VariantType} cannot have value None")
         if self.Dimensions is None and isinstance(self.Value, (list, tuple)):
             dims = get_shape(self.Value)
             if len(dims) > 1: