umijs,在禁用cssModule后，如何配置postcss-loader?

[fallred]

文档https://umijs.org/zh/guide/faq.html#%E5%A6%82%E4%BD%95%E9%85%8D%E7%BD%AE%E9%A2%9D%E5%A4%96%E7%9A%84-loader。文档没有具体的配置postcss部分，我配置.umirc文件后，具体代码如下：
import plugins from './postcss.config';
export default {
plugins: [
[
'umi-plugin-react',
{
dva: true
}
]
],
sass: {},
chainWebpack(config, { webpack }) {
// 设置 alias
//config.resolve.alias.set('a', 'path/to/a');

    // 删除进度条插件
    //config.plugins.delete('progress');

    config.module.rule('css')
    .test(/\.(scss|css|less)$/)
    .use('css-loader')
    .loader('postcss-loader')
},
disableCSSModules: true,
extraPostCSSPlugins: plugins,
cssLoaderOptions: {}

};
postcss.config.js文件代码如下：
const plugins = [
require('postcss-at-rules-variables')(),
require('postcss-import')(),
require('postcss-mixins')(),
require('postcss-bem')({
defaultNamespace: '',
style: 'suit'
})
];

module.exports = plugins;
npm run satrt 启动之后，一直报编译错误：
Module build failed (from ./node_modules/mini-css-extract-plugin/dist/loader.js):
ModuleBuildError: Module build failed (from ./node_modules/mini-css-extract-plugin/dist/loader.js):