Warning on database config collector - Object cannot be cast from DBNull to other types

## Environment

- **SQL Server Version**: Microsoft SQL Server Express (64-bit) 13.0.6475.1
- **Windows Version**: Microsoft Windows NT 6.3 (17763)
- **Component**: Lite
- **Performance Monitor Version**: 1.2

## Error Messages

```
database_config	WARNING	5	1	4	80	1,5 s	19/02/2026 17:21	19/02/2026 17:27	19/02/2026 17:27	Object cannot be cast from DBNull to other types.
```
