Refactor water heater value selector widget

lib/pages/routines/widgets/routine_dialogs/water_heater/water_heater_value_selector_widget.dart

@@ -28,7 +28,11 @@ class WaterHeaterValueSelectorWidget extends StatelessWidget {
   Widget build(BuildContext context) {
     final selectedFn = whFunctions.firstWhere(
       (f) => f.code == selectedFunction,
-      orElse: () => throw Exception('Function $selectedFunction not found'),
+      orElse: () => WHSwitchFunction(
+        deviceId: '',
+        deviceName: '',
+        type: '',
+      ),
     );
     if (selectedFunction == 'countdown_1') {
       return Column(