Umi启动项目出现报错：Path must be a string.

1.问题描述
在使用Umi启动项目的时候，出现了以下报错：

2.出现原因
package.json依赖的插件版本与现在umi版本发生冲突，具体如下所示：

{
  "name": "umi-test",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "start": "umi dev",
    "build": "umi build"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "antd": "^3.13.0",
    "axios": "^0.18.0",
    "umi-plugin-react": "^1.4.2"
  }
}

而Umi3中发生了以下修改：

3.解决办法
(1)修改package.json中的"umi-plugin-react"

{
  "name": "umi-test",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "start": "umi dev",
    "build": "umi build"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "antd": "^3.13.0",
    "axios": "^0.18.0",
    "@umijs/preset-react": "^1.4.2"
  }
}

(2)修改config.js
修改前：

export default {
  plugins: [
    [
      "umi-plugin-react",
      {
        antd: true,
        dva: true
      }
    ]
  ],
  routes: [
      //+++
  ]
};

修改后：

export default {
  dva:{},
  antd:{},
  routes: [
      //+++
  ]
};