ReferenceError: __VUE_OPTIONS_API__, __VUE_PROD_DEVTOOLS__ is not defined

问题：浏览器控制台会输出warning，提示：ReferenceError: __VUE_OPTIONS_API__, __VUE_PROD_DEVTOOLS__ is not defined.

官方文档解释为：

Starting with 3.0.0-rc.3, esm-bundler builds now exposes global feature flags that can be overwritten at compile time:

• __VUE_OPTIONS_API__ (enable/disable Options API support, default: true)
• __VUE_PROD_DEVTOOLS__ (enable/disable devtools support in production, default: false)

The build will work without configuring these flags, however it is strongly recommended to properly configure them in order to get proper tree-shaking in the final bundle. To configure these flags:

• webpack: use DefinePlugin
• Rollup: use @rollup/plugin-replace
• Vite: configured by default, but can be overwritten using the define option

Note: the replacement value must be boolean literals and cannot be strings, otherwise the bundler/minifier will not be able to properly evaluate the conditions.

就是在vue@3.0.0-rc.3版本开始，强烈推荐我们设置  __VUE_OPTIONS_API__, __VUE_PROD_DEVTOOLS__  两个属性，
例如使用 DefinePlugin，我们在webpack的plugins中可以这样设置：

new webpack.DefinePlugin({
    '__VUE_OPTIONS_API__': true,
    '__VUE_PROD_DEVTOOLS__': false
})

PS: 这里要注意设置的值得是boolean类型！

设置完控制台将不会再提示！

参考文档：

Bundler Build Feature Flags：https://github.com/vuejs/core/tree/main/packages/vue#bundler-build-feature-flags