Issue regarding flutter-slider (errors_patch.dart -> AssertionError

I'm fairly new to Flutter, and I was trying to implement a horizontal-slider with divisions using the external syncfusion_flutter_sliders library.
Here's my attempt at the implementation:

class SliderExample extends StatefulWidget {
  const SliderExample({super.key});
  @override
  State<SliderExample> createState() => _SliderExampleState();
}

class _SliderExampleState extends State<SliderExample> {
  final double _min = 0;
  final double _max = 100;
  double _value = 40.0;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: SfSlider(
          min: _min,
          max: _max,
          value: _value,
          interval: 20,
          showTicks: true,
          showLabels: true,
          onChanged: (dynamic newValue) {
            setState(() {
              _value = newValue;
            });
          },
        ),
      ),
    );
  }
}

The above stateful widget when called in another stateless route, throws the following error:

ERROR -> errors_patch.dart

@pragma("vm:external-name", "AssertionError_throwNew")
external static _doThrowNew(
    int assertionStart, int assertionEnd, Object? message);

CALL

return Scaffold(
  body:
    Container(
      alignment: Alignment.center,
      decoration: const BoxDecoration(
          gradient: LinearGradient(colors: [Colors.orangeAccent, Colors.deepOrange]),
      ),
      child: ListView(
        children: const <Widget>[
          Text('\n\n\nHow Many People Did You Meet Today?',
              textAlign: TextAlign.justify,
              style: TextStyle(fontSize: 40, color: Colors.black, fontWeight: FontWeight.bold)
          ),
          MaterialApp(
            home: SliderExample(), // <-- HERE
          )
        ]
      ),
  ),
);

Resources to the flutter library followed: https://pub.dev/packages/syncfusion_flutter_sliders ;p.s. Excuse me if it's an elementary fix, in view of the fact that I'm trying to learn by making an app from scratch using the Flutter Docs.

CodePudding user response：

Try changing this part of your code to this

child: ListView(
        children: const <Widget>[
          Text('\n\n\nHow Many People Did You Meet Today?',
              textAlign: TextAlign.justify,
              style: TextStyle(fontSize: 40, color: Colors.black, fontWeight: FontWeight.bold)
          ),
          SliderExample(),
        ]
      ),

You shouldn't call MaterialApp(home: ) there.

And in _SliderExampleState, change the following part to the one below

Widget build(BuildContext context) {
  return SfSlider(
    min: _min,
    max: _max,
    value: _value,
    interval: 20,
    showTicks: true,
    showLabels: true,
    onChanged: (dynamic newValue) {
      setState(() {
        _value = newValue;
      });
    },
  );
}

Remove the wrapping in Scaffold and Center.