Accessing the package details seems to return invalid data.

I'm trying to access the name of the main package from Devtools running inside the browser. It looks like I'm getting invalid data back.

```dart
var rootInfo = serviceManager.rootInfoNow();

var package = rootInfo.package;
// Returns: "file:"

var library = rootInfo.library;
// Returns: "file:///Users/viktor/Projects/tests/gui_1/gui_1_server/bin/main.dart"
```