Update app.py

app.py

@@ -74,10 +74,13 @@ def initialize(arxivcode):
 rag_chain = None 
 
 def handle_prompt(message, history, arxivcode): 
-    if rag_chain is None: 
+    try:
+        rag_chain
+    except UnboundLocalError:
         # initialize RAG chain 
         # RAG chain
         rag_chain = initialize(arxivcode)
+        global rag_chain
         
     try:
         # Stream output