fix(converter): Fix param is None error

capella2polarion/converters/element_converter.py

@@ -139,7 +139,7 @@ def serialize(self, uuid: str) -> data_models.CapellaWorkItem | None:
                     ...,
                     data_models.CapellaWorkItem,
                 ] = getattr(self, f"_{converter}")
-                serializer(converter_data, **params)
+                serializer(converter_data, **(params or {}))
             except Exception as error:
                 converter_data.errors.add(error.args[0])
                 converter_data.work_item = None