Update app.py

app.py

@@ -51,6 +51,8 @@ async def syncMessages():
         for dir in os.listdir("data"):
             i += 1
             with dirs[i]:
+                if files == []:
+                  return 0
                 files = st.tabs(os.listdir("data/" + dir))
                 k = -1
                 for file in os.listdir("data/" + dir):