Sqlflite - 用于空值的空检查运算符

Question

我收到 - 在尝试测试我的 sqflite 应用程序时，在空值上使用了空检查运算符此错误。甚至认为代码在模拟器中工作。但它没有通过测试。 请帮忙。

import 'dart:io';

import 'package:path_provider/path_provider.dart';
import 'package:sqflite/sqflite.dart';

class DbHelper {
  static final DbHelper instance = DbHelper._instance();
  DbHelper._instance();
  static Database? _db;
  Future<Database> get db async {
    if (_db != null) return db;
    _db = await _initDb();
    return _db!;
  }

  Future<Database> _initDb() async {
    Directory dir = await getApplicationDocumentsDirectory();
    String path = dir.path + '/account_keeper.db';
    final accountManagerDb = await openDatabase(
      path,
      version: 1,
      onCreate: _createDb,
    );
    return accountManagerDb;
  }

  void _createDb(Database db, int version) async {
    // Table 1- BusinessProfile Profile
    print('creating db');
    print('--create database--');
    const String businessProfileTable = 'businessProfile_table';
    String businessId = 'id';
    String businessName = 'businessName';

    await db.execute(
      '''
        CREATE TABLE 
          $businessProfileTable(
              $businessId INTEGER PRIMARY KEY AUTOINCREMENT,
              $businessName TEXTT )''',
    );
  }
}