Update app.py

app.py

@@ -6,6 +6,8 @@ genai.configure(api_key=os.getenv("GOOGLE_PALM_KEY"))
 
 
 def generate(prompt, history, system):
+  history = [['' if item is None else item for item in sub_array] for sub_array in history]
+    
   sub_arrays_as_strings = [' '.join(sub_array) for sub_array in history]
   result_string = ' '.join(sub_arrays_as_strings)
   response = genai.chat(