Update app.py

app.py

@@ -105,8 +105,8 @@ with row3_col5:
     if st.button(f"Select Image ↑", key="button_8"):
         st.session_state.image = img_8
 
-# model
-if st.session_state.model is None:
+# load model
+if 'model' not in st.session_state:
     session_state.model = YOLO("/home/user/app/models/head_model/best.pt")  # load        
 
 #####