[BUG] FileSaver MacCatalyst crushes when i dont have write access to the given filepath

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Did you read the "Reporting a bug" section on Contributing file?

- [X] I have read the "Reporting a bug" section on Contributing file: https://github.com/CommunityToolkit/Maui/blob/main/CONTRIBUTING.md#reporting-a-bug

### Current Behavior

Start FileSaver (no special setup needed, as far i can see).
The Saver showing my HD (main) on the path. If i don't change it to f.e. my home dir, the sw crushing when i accept a choosen (upload) file.

This is esp bad, cause its the STARTup situation.

Feature: I would also like it have an option i can hand over at startup (where to start on path). btw: And to see the saver in my own language (its always in english, right now).

### Expected Behavior

If no write access, give an error back. Not crush silently (i can only see a message in debug similar to "missing access rights".

### Steps To Reproduce

see "Current behaviour"

### Link to public reproduction project repository

see your own examples

### Environment

```markdown
- .NET MAUI CommunityToolkit: 6.0.0
- OS: MacCatalyst
- .NET MAUI: 8.0.0.163
```

### Anything else?

_No response_