Update app.py

app.py

@@ -125,8 +125,10 @@ def add_file(history, task_history, file):
     return history, task_history
 
 def predict(_chatbot, task_history) -> tuple:
-    print("predict called")
+    if not _chatbot:
+        return _chatbot, task_history
     chat_query, chat_response = _chatbot[-1]
+    print("predict called")
     if isinstance(chat_query, tuple):
         chat_query = chat_query[0]
         query = [{'image': chat_query}]