Make sure to Init device_list with []

Author: bouwew

plugwise/__init__.py

@@ -126,6 +126,7 @@ def _all_device_data(self) -> None:
         """
         self._update_gw_devices()
         self.device_items = self._count
+        self.device_list = []
         for device in self.gw_devices:
             self.device_list.append(device)