编译React App时，React中的模块构建错误：“未知插件“ @ babel / plugin-proposal-decorators”

Question

我正在组装一个小型React App，并尝试将MobX纳入依赖项。下面是babel的package.json设置。

"babel": {
"presets": [
  "@babel/preset-env",
  "react-app"
],
"plugins": [
  [
    "@babel/plugin-proposal-decorators",
    {
      "legacy": true
    }
  ],
  [
    "@babel/plugin-proposal-class-properties",
    {
      "loose": true
    }
   ]
 ]
},
"devDependencies": {
"@babel/plugin-proposal-decorators": "^7.1.2",
"babel-plugin-transform-decorators-legacy": "^1.3.5"
}

启动服务器时出现的实际错误如下：

./src/index.js
Module build failed: ReferenceError: Unknown plugin "@babel/plugin-proposal- 
decorators" specified in 
"/Users/briankaty1/Desktop/mobx/aquastars/react_aquastars/package.json" at 0, 
attempted to resolve relative to 
"/Users/briankaty1/Desktop/mobx/aquastars/react_aquastars"

任何帮助将不胜感激。