Update app.py

app.py

@@ -455,8 +455,11 @@ async def websocket_handler(request):
     ws = web.WebSocketResponse()
     await ws.prepare(request)
     connected_clients.add(ws)
-    try: async for msg in ws: pass
-    finally: connected_clients.remove(ws)
+    try:
+        async for msg in ws:
+            pass
+    finally:
+        connected_clients.remove(ws)
     return ws
 
 async def handle_index(request):