[Bug Report] 在nuxt中使用，组件无法通过npm run dev，loader报错

### VUX version
2.9.2

### OS/Browsers version
win10/Chrome 版本 71.0.3578.98（正式版本） （32 位）

### Vue version
2.5.21

### Code

```html
package.json
```
"dependencies": {
"@nuxtjs/axios": "^5.0.0",
"cross-env": "^5.2.0",
"express": "^4.16.3",
"nuxt": "^2.0.0",
"vux": "^2.9.2"
},
"devDependencies": {
"babel-preset-env": "^1.7.0",
"less": "^3.9.0",
"less-loader": "^4.1.0",
"nodemon": "^1.11.0",
"vux-loader": "^1.2.9"
}
```

nuxt.config.js
与https://github.com/airyland/vux/tree/v2/ssr/nuxt给出的例子一样
```

### Steps to reproduce
按照https://github.com/airyland/vux/tree/v2/ssr/nuxt给出的例子进行配置，然后npm run dev，出现好多个：
```
> log friendly-errors »
@ ./node_modules/vux/index.js 60:0-49 166:0-327:1
@ ./plugins/vux/vux-components.js
@ ./.nuxt/index.js
@ ./.nuxt/client.js
@ multi webpack-hot-middleware/client?name=client&reload=true&timeout=30000&path=/__webpack_hmr/client ./.nuxt/client.j
s
× error friendly-errors » in ./node_modules/vux/src/components/grid/grid-item.vue
> log friendly-errors » Module parse failed: Unexpected token (3:0)
You may need an appropriate loader to handle this file type.
| import { render, staticRenderFns } from "./grid-item.vue?vue&type=template&id=5fee7ff2&"
| import script from "./grid-item.vue?vue&type=script&lang=js&"
> ../../../../vux-loader/src/script-loader.js!export * from "./grid-item.vue?vue&type=script&lang=js&"
| import style0 from "./grid-item.vue?vue&type=style&index=0&lang=less&"
```

好像基本上都是说loader不正确

### What is Expected?
npm run dev应该至少能通过才能做后续的开发。

### What is actually happening?
npm run dev无法通过。