error when working with web3dart in flutter

Question

import 'dart:html';
import 'package:web3dart/web3dart.dart';

import 'package:flutter/material.dart';

class Home extends StatefulWidget {
  const Home({super.key});

  @override
  State<Home> createState() => _HomeState();
}

class _HomeState extends State<Home> {
  Client? httpClient;
  Web3Client? ethClient;

  @override
  Widget build(BuildContext context) {
    return Container();
  }
}

when connecting Web3 Client erroneously

error text : Target of URI doesn't exist: 'package:web3dart/web3dart.dart'. Try creating the file referenced by the URI, or try using a URI for a file that does exist.darturi_does_not_exist

error text : Undefined class 'Web3Client'. Try changing the name to the name of an existing class, or creating a class with the name 'Web3Client'.dartundefined_class