diff --git a/api/onnx_web/chain/result.py b/api/onnx_web/chain/result.py
index bd283b1a..813f5863 100644
--- a/api/onnx_web/chain/result.py
+++ b/api/onnx_web/chain/result.py
@@ -42,7 +42,7 @@ class StageResult:
         elif self.images is not None:
             return len(self.images)
         else:
-            raise ValueError("empty stage result")
+            return 0
 
     def as_numpy(self) -> List[np.ndarray]:
         if self.arrays is not None:
@@ -50,7 +50,7 @@ class StageResult:
         elif self.images is not None:
             return [np.array(i) for i in self.images]
         else:
-            raise ValueError("empty stage result")
+            return []
 
     def as_image(self) -> List[Image.Image]:
         if self.images is not None:
@@ -58,7 +58,7 @@ class StageResult:
         elif self.arrays is not None:
             return [Image.fromarray(np.uint8(i), shape_mode(i)) for i in self.arrays]
         else:
-            raise ValueError("empty stage result")
+            return []
 
 
 def shape_mode(arr: np.ndarray) -> str:
diff --git a/api/onnx_web/utils.py b/api/onnx_web/utils.py
index 6ef953c3..d047ec0d 100644
--- a/api/onnx_web/utils.py
+++ b/api/onnx_web/utils.py
@@ -75,13 +75,13 @@ def get_from_list(
 
 
 def get_from_map(
-    args: Any, key: str, values: Dict[str, TElem], defaultKey: str
+    args: Any, key: str, values: Dict[str, TElem], default_key: str
 ) -> TElem:
-    selected = args.get(key, defaultKey)
+    selected = args.get(key, default_key)
     if selected in values:
         return values[selected]
     else:
-        return values[defaultKey]
+        return values[default_key]
 
 
 def get_not_empty(args: Any, key: str, default: TElem) -> TElem: