fixes [[RangeSlider] [Flutter 3.10] LateInitializationError: Field '_startThumbCenter@280317193' has not been initialized.](https://github.com/flutter/flutter/issues/126648)

### Code sample (Run it on iOS)

<details>
<summary>expand to view the code sample</summary> 

```dart
import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Example(),
    );
  }
}

class Example extends StatelessWidget {
  const Example({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: ListView(
        children: <Widget>[
          const SizedBox(
            height: 1000,
            child: Placeholder(),
          ),
          RangeSlider(
            values: const RangeValues(0.25, 0.75),
            onChanged: (value) {},
          ),
        ],
      ),
    );
  }
}
```

</details>