rydmike/main.dart

## main.dart
import 'dart:math' as math;
import 'package:flutter/material.dart';

void main() {
  runApp(WebCrashDemo());
}

class WebCrashDemo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        primarySwatch: Colors.indigo,
        scaffoldBackgroundColor: Colors.grey[100],
        buttonTheme: ButtonThemeData(
          colorScheme: ColorScheme.fromSwatch(primarySwatch: Colors.indigo),
          textTheme: ButtonTextTheme.primary,
        ),
      ),
      debugShowCheckedModeBanner: false,
      home: HomePage(),
    );
  }
}

class HomePage extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return _HomePageState();
  }
}

class _HomePageState extends State<HomePage> {
  bool _crashMe = false;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Circle Gradient Crash on Web'),
        centerTitle: true,
        elevation: 0,
      ),
      body: Column(
        children: [
          // And then some gap space too
          const SizedBox(height: 20),
          const Text('Shader createShader crashes on WEB'),
          const SizedBox(height: 20),
          Center(
            child: SizedBox(
              width: 170,
              height: 170,
              child: ColorCircle(crashMe: _crashMe),
            ),
          ),

          const SizedBox(height: 10),
          Center(
            child: SizedBox(
              width: 450,
              child: SwitchListTile(
                title: const Text('Crash me on WEB'),
                subtitle:
                    const Text('This option crashes on web, but only on WEB! '
                        'Turn on only on none WEB! If you run this code '
                        'on an emulator or desktop it works fine.'),
                value: _crashMe,
                onChanged: (value) {
                  setState(() {
                    _crashMe = value;
                  });
                },
              ),
            ),
          ),

          const SizedBox(height: 10),
        ],
      ),
    );
  }
}

// *****************************************************************************

class ColorCircle extends StatelessWidget {
  const ColorCircle({
    Key key,
    this.crashMe = false,
  }) : super(key: key);

  /// Set to true to make the shader that crashes on web!
  final bool crashMe;

  @override
  Widget build(BuildContext context) {
    return CustomPaint(
      painter: _WheelPainter(crashMe: crashMe),
    );
  }
}

class _WheelPainter extends CustomPainter {
  _WheelPainter({this.crashMe = false});
  final bool crashMe;

  static double radius(Size size) =>
      math.min(size.width, size.height).toDouble() / 2 - 8;

  @override
  void paint(Canvas canvas, Size size) {
    final Offset center = Offset(size.width / 2, size.height / 2);
    final double radius = _WheelPainter.radius(size);

    const SweepGradient colorWheelGradient =
        SweepGradient(center: Alignment.bottomRight, colors: [
      Color.fromARGB(255, 255, 0, 0),
      Color.fromARGB(255, 255, 255, 0),
      Color.fromARGB(255, 0, 255, 0),
      Color.fromARGB(255, 0, 255, 255),
      Color.fromARGB(255, 0, 0, 255),
      Color.fromARGB(255, 255, 0, 255),
      Color.fromARGB(255, 255, 0, 0),
    ]);

    // If we create a shader from the above SweepGraident, we get
    // a crash on web, but only on web.
    final Shader sweepShader = crashMe
        ? colorWheelGradient.createShader(Rect.fromLTWH(0, 0, radius, radius))
        : null;

    canvas.drawCircle(
        center,
        radius,
        Paint()
          ..style = PaintingStyle.stroke
          ..strokeWidth = 16
          ..shader = sweepShader);
  }

  @override
  bool shouldRepaint(_WheelPainter other) => true;
}
	import 'dart:math' as math;
	import 'package:flutter/material.dart';

	void main() {
	runApp(WebCrashDemo());
	}

	class WebCrashDemo extends StatelessWidget {
	@override
	Widget build(BuildContext context) {
	return MaterialApp(
	theme: ThemeData(
	primarySwatch: Colors.indigo,
	scaffoldBackgroundColor: Colors.grey[100],
	buttonTheme: ButtonThemeData(
	colorScheme: ColorScheme.fromSwatch(primarySwatch: Colors.indigo),
	textTheme: ButtonTextTheme.primary,
	),
	),
	debugShowCheckedModeBanner: false,
	home: HomePage(),
	);
	}
	}

	class HomePage extends StatefulWidget {
	@override
	State<StatefulWidget> createState() {
	return _HomePageState();
	}
	}

	class _HomePageState extends State<HomePage> {
	bool _crashMe = false;

	@override
	Widget build(BuildContext context) {
	return Scaffold(
	appBar: AppBar(
	title: const Text('Circle Gradient Crash on Web'),
	centerTitle: true,
	elevation: 0,
	),
	body: Column(
	children: [
	// And then some gap space too
	const SizedBox(height: 20),
	const Text('Shader createShader crashes on WEB'),
	const SizedBox(height: 20),
	Center(
	child: SizedBox(
	width: 170,
	height: 170,
	child: ColorCircle(crashMe: _crashMe),
	),
	),

	const SizedBox(height: 10),
	Center(
	child: SizedBox(
	width: 450,
	child: SwitchListTile(
	title: const Text('Crash me on WEB'),
	subtitle:
	const Text('This option crashes on web, but only on WEB! '
	'Turn on only on none WEB! If you run this code '
	'on an emulator or desktop it works fine.'),
	value: _crashMe,
	onChanged: (value) {
	setState(() {
	_crashMe = value;
	});
	},
	),
	),
	),

	const SizedBox(height: 10),
	],
	),
	);
	}
	}

	// *****************************************************************************

	class ColorCircle extends StatelessWidget {
	const ColorCircle({
	Key key,
	this.crashMe = false,
	}) : super(key: key);

	/// Set to true to make the shader that crashes on web!
	final bool crashMe;

	@override
	Widget build(BuildContext context) {
	return CustomPaint(
	painter: _WheelPainter(crashMe: crashMe),
	);
	}
	}

	class _WheelPainter extends CustomPainter {
	_WheelPainter({this.crashMe = false});
	final bool crashMe;

	static double radius(Size size) =>
	math.min(size.width, size.height).toDouble() / 2 - 8;

	@override
	void paint(Canvas canvas, Size size) {
	final Offset center = Offset(size.width / 2, size.height / 2);
	final double radius = _WheelPainter.radius(size);

	const SweepGradient colorWheelGradient =
	SweepGradient(center: Alignment.bottomRight, colors: [
	Color.fromARGB(255, 255, 0, 0),
	Color.fromARGB(255, 255, 255, 0),
	Color.fromARGB(255, 0, 255, 0),
	Color.fromARGB(255, 0, 255, 255),
	Color.fromARGB(255, 0, 0, 255),
	Color.fromARGB(255, 255, 0, 255),
	Color.fromARGB(255, 255, 0, 0),
	]);

	// If we create a shader from the above SweepGraident, we get
	// a crash on web, but only on web.
	final Shader sweepShader = crashMe
	? colorWheelGradient.createShader(Rect.fromLTWH(0, 0, radius, radius))
	: null;

	canvas.drawCircle(
	center,
	radius,
	Paint()
	..style = PaintingStyle.stroke
	..strokeWidth = 16
	..shader = sweepShader);
	}

	@override
	bool shouldRepaint(_WheelPainter other) => true;
	}