Fix lint errors

optuna_dashboard/_importance.py

@@ -1,7 +1,6 @@
 from __future__ import annotations
 
 import threading
-from typing import List
 from typing import TYPE_CHECKING
 import warnings
 
@@ -63,9 +62,7 @@ def get_param_importance_from_trials_cache(
 
     cache_key = f"{study_id}:{objective_id}"
     with param_importance_cache_lock:
-        cache_n_trial, cache_importance = param_importance_cache.get(
-            cache_key, (0, {"param_importances": []})
-        )
+        cache_n_trial, cache_importance = param_importance_cache.get(cache_key, (0, []))
         if n_completed_trials == cache_n_trial:
             return cache_importance
 

optuna_dashboard/_note.py

@@ -8,8 +8,8 @@ from optuna.storages import BaseStorage
 
 
 if TYPE_CHECKING:
-    from typing import TypedDict
     from typing import Optional
+    from typing import TypedDict
 
     NoteType = TypedDict(
         "NoteType",
@@ -29,7 +29,7 @@ def note_ver_key(trial_id: Optional[int]) -> str:
     return f"dashboard:{trial_id}:note_ver"
 
 
-def note_str_key_prefix(trial_id: int) -> str:
+def note_str_key_prefix(trial_id: Optional[int]) -> str:
     prefix = "dashboard:note_str:"
     if trial_id is None:
         return prefix