updated ui

app.py

@@ -138,12 +138,13 @@ async def handle_message(message: cl.Message):
 
 @cl.on_chat_start
 async def handle_chat_start():
-    # Ensure session data is initialized
-    if "message_history" not in cl.user_session:
+    # Check if "message_history" is None
+    if cl.user_session.get("message_history") is None:
         cl.user_session.set("message_history", [])
-    
-    if "food_data" not in cl.user_session:
-        cl.user_session.set("food_data", None)  # Explicitly initialize to None
+
+    # Check if "food_data" is None
+    if cl.user_session.get("food_data") is None:
+        cl.user_session.set("food_data", None)
 
     welcome_message = """
 ## Welcome to the USDA Food Assistant!
@@ -170,7 +171,6 @@ The dataset powering this application is available on HuggingFace Datasets, link
 To learn more about how this dataset & the USDA Food Assistant were created, check out the blog post, linked [here](https://jacktol.net/posts/building_a_data_pipeline_for_usda_fooddata_central/).
 
 The full code for the data pipeline and the assistant can be found on GitHub, linked [here](https://github.com/jack-tol/usda-food-data-pipeline).
-
 """
-    
+
     await cl.Message(content=welcome_message).send()