如何在使用flutter_svg包时修复此nullOk错误？

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

class SvgExample extends StatelessWidget {
  final String svgPath;

  SvgExample({required this.svgPath});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('SVG Example'),
      ),
      body: Center(
        child: SvgPicture.asset(
          svgPath,
          width: 200,
          height: 200,
          color: Colors.blue,
        ),
      ),
    );
  }
}

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: SvgExample(svgPath: 'assets/images/example.svg'),
    );
  }
}

final String svgPath = 'assets/images/example.svg';
if (svgPath != null && svgPath.isNotEmpty) {
  return SvgPicture.asset(
    svgPath,
    width: 200,
    height: 200,
    color: Colors.blue,
  );
} else {
  return Text('SVG file not found');
}