remove None default assignment

app.py

@@ -212,7 +212,7 @@ with gr.Blocks(title=title) as demo:
                 history = history or []
                 return "", history + [[message, None]]
 
-            def respond(history=None, token_count, temperature, top_p, presence_penalty, count_penalty):
+            def respond(history, token_count, temperature, top_p, presence_penalty, count_penalty):
                 instruction = history[-1][0]
                 history[-1][1] = ""