使用官网示例
```javascript
plugins: ['@vuepress/back-to-top']
出现错误
```javascript
warning An error was encountered in plugin "@vuepress/back-to-top"
使用官网示例
```javascript
plugins: ['@vuepress/back-to-top']
出现错误
```javascript
warning An error was encountered in plugin "@vuepress/back-to-top"