Update app.py

app.py

@@ -258,7 +258,7 @@ def Chart_Generator(history):
 
     message = history[-1][0]
     if '#chart' in message:
-        message = user_input.split('#chart', 1)[1].strip()
+        message = message.split('#chart', 1)[1].strip()
         chart_url = f"https://quickchart.io/natural/{message}"
         response = requests.get(chart_url)