🚧 Decrease verbosity of errors upon 429 answers from RTE API

Goal is to avoid raising verbose errors when this is a "normal" error.
In practice it should not change the current behavior since refresh
period is calibrated to avoid this. 429 should happen only at startup
(or when removing/re-adding the integration)

custom_components/rte_ecowatt/__init__.py

@@ -197,6 +197,11 @@ async def update_method(self):
             if api_result.status == 429:
                 # a code 429 is expected when requesting more often than every 15minutes and not using the sandbox url
                 # FIXME(kamaradclimber): avoid this error when home assistant is restarting by storing state and last update
+                if self.data is not None:
+                    _LOGGER.warn(
+                        "Error communicating with RTE API: requests too frequent. Using old data"
+                    )
+                    return self.data
                 raise UpdateFailed(
                     f"Error communicating with RTE API: requests too frequent to RTE API"
                 )