Fix numpy array boolean ambiguity in image None check

app.py

@@ -170,8 +170,10 @@ def gradio_inference(image, model_display_name, conf_threshold):
             model_key = key
             break
 
-    if model_key is None or image is None:
+    if model_key is None:
         return image
+    if image is None:
+        return None
 
     session = get_session(model_key)
     img_bgr = cv2.cvtColor(image, cv2.COLOR_RGB2BGR)
@@ -206,7 +208,9 @@ def api_inference(image, model_display_name, conf_threshold):
             model_key = key
             break
 
-    if model_key is None or image is None:
+    if model_key is None:
+        return []
+    if image is None:
         return []
 
     session = get_session(model_key)