diff --git a/slam/backend/mrob_backend.py b/slam/backend/mrob_backend.py
index e2a9772..d0356c1 100644
--- a/slam/backend/mrob_backend.py
+++ b/slam/backend/mrob_backend.py
@@ -106,7 +106,7 @@ def __get_unused_features(self) -> List[int]:
         """
         try:
             robust_mask = self._graph.get_eigen_factors_robust_mask()
-        except AttributeError as e:
+        except AttributeError:
             return []
 
         unused_features = []