Fix Freebox call sensor when no call in history (#40001)

homeassistant/components/freebox/sensor.py

@@ -146,6 +146,7 @@ class FreeboxCallSensor(FreeboxSensor):
     def async_update_state(self) -> None:
         """Update the Freebox call sensor."""
         self._call_list_for_type = []
+        if self._router.call_list:
             for call in self._router.call_list:
                 if not call["new"]:
                     continue