从eslint>=7.5.0开始，本地支持空位合并运算符.

Nullish coalescing operator is natively supported starting from eslint>=7.5.0.

最简单的方法是在package.json中设置ES2020:

The easiest is set ES2020 in your package.json:

{
  "eslintConfig":
  {
    "parserOptions":
    {
      "ecmaVersion": 2020
    }
  }
}