fix by review

optuna_dashboard/_app.py

@@ -275,12 +275,8 @@ def create_app(
             response.status = 400  # Bad request
             return {"reason": "You need to set best_trials and worst_trials"}
 
-        try:
-            preferences = [(best, worst) for best in best_trials for worst in worst_trials]
-            report_preferences(study_id, storage, preferences)
-        except Exception as e:
-            response.status = 500
-            return {"reason": f"Internal server error: {e}"}
+        preferences = [(best, worst) for best in best_trials for worst in worst_trials]
+        report_preferences(study_id, storage, preferences)
 
         response.status = 204
         return {}

optuna_dashboard/preferential/_system_attrs.py

@@ -14,7 +14,7 @@ _SYSTEM_ATTR_PREFIX_PREFERENCE = "preference:values"
 def report_preferences(
     study_id: int,
     storage: BaseStorage,
-    preferences: list[tuple[int, int]],  # element is number of trail
+    preferences: list[tuple[int, int]],
 ) -> None:
     key = _SYSTEM_ATTR_PREFIX_PREFERENCE + str(uuid.uuid4())
     storage.set_study_system_attr(