Update app.py

app.py

@@ -187,18 +187,20 @@ New input: {input}
 Thought: Do I need to use a tool? {agent_scratchpad}"""
 
 def cut_dialogue_history(history_memory, keep_last_n_words = 500):
+    if history_memory is None or len(history_memory) == 0:
+        print("history memory is none.")
+        return history_memory
     tokens = history_memory.split()
     n_tokens = len(tokens)
     print(f"history_memory:{history_memory}, n_tokens: {n_tokens}")
     if n_tokens < keep_last_n_words:
         return history_memory
-    else:
-        paragraphs = history_memory.split('\n')
-        last_n_tokens = n_tokens
-        while last_n_tokens >= keep_last_n_words:
-            last_n_tokens = last_n_tokens - len(paragraphs[0].split(' '))
-            paragraphs = paragraphs[1:]
-        return '\n' + '\n'.join(paragraphs)
+    paragraphs = history_memory.split('\n')
+    last_n_tokens = n_tokens
+    while last_n_tokens >= keep_last_n_words:
+        last_n_tokens -= len(paragraphs[0].split(' '))
+        paragraphs = paragraphs[1:]
+    return '\n' + '\n'.join(paragraphs)