Fix issue when getting dict of MetaOperator.

aidge_core/export_utils/node_export.py

@@ -133,8 +133,7 @@ class ExportNode(ABC):
         self.node = aidge_node
         self.operator = aidge_node.get_operator()
         # Attributes are auto fetched from aidge operators
-        self.attributes = self.operator.attr.dict(
-        ) if self.operator.attr is not None else {}
+        self.attributes = {}  if isinstance(self.operator, aidge_core.MetaOperator_Op) or self.operator.attr is None else self.operator.attr.dict()
         self.attributes["node"] = self.node
         self.attributes["name"] = self.node.name()
         self.attributes["nb_in"] = self.node.get_nb_inputs()