Update app.py

app.py

@@ -145,8 +145,8 @@ def unpack_zip_file(filename:str,db:LangChainFAISS,progress):
 
         if 'index.faiss' in [item.lower() for item in contents]:
             db2 = LangChainFAISS.load_local(tmp_directory, embeddings, allow_dangerous_deserialization=True)
-            db.merge_from(db2)
-            return db
+            db2.merge_from(db)
+            return db2
         
         for file in contents:
             if file.lower().endswith('.docx'):