Guard against multiple client creations (#2809)

supervisor/homeassistant/websocket.py

@@ -86,9 +86,14 @@ class HomeAssistantWebSocket(CoreSysAttributes):
         """Initialize Home Assistant object."""
         self.coresys: CoreSys = coresys
         self._client: Optional[WSClient] = None
+        self._lock: asyncio.Lock = asyncio.Lock()
 
     async def _get_ws_client(self) -> WSClient:
         """Return a websocket client."""
+        async with self._lock:
+            if self._client is not None:
+                return self._client
+
             await self.sys_homeassistant.api.ensure_access_token()
             client = await WSClient.connect_with_auth(
                 self.sys_websession_ssl,