Add null check in ApiClient.getList to handle cases where response.data is null, returning empty list instead of throwing cast error

b0esche_cloud/lib/services/api_client.dart

@@ -125,7 +125,9 @@ class ApiClient {
   }) async {
     try {
       final response = await _dio.get(path, queryParameters: queryParameters);
-      return (response.data as List).map(fromJson).toList();
+      final data = response.data;
+      if (data == null) return [];
+      return (data as List).map(fromJson).toList();
     } on DioException catch (e) {
       throw _handleError(e);
     }