Fix the bug while renaming a study with maximize direction

optuna_dashboard/_app.py

@@ -139,8 +139,12 @@ def create_app(
             response.status = 404  # Not found
             return {"reason": f"study_id={study_id} is not found"}
 
+        summary = get_study_summary(storage, study_id)
+        if summary is None:
+            response.status = 500
+            return {"reason": "Failed to load the study"}
         try:
-            dst_study = optuna.create_study(storage=storage, study_name=dst_study_name)
+            dst_study = optuna.create_study(storage=storage, study_name=dst_study_name, directions=summary.directions)
             dst_study.add_trials(src_study.get_trials(deepcopy=False))
         except DuplicatedStudyError:
             response.status = 400  # Bad request