title: Is there a problem when use of mobx in my project , the error is 'Support for the experimental syntax 'decorators-legacy' isn't currently enabled'
body: <p>I configured my package.json and babelrc but I got some errors when I used decorators. </p>
  
  <p>I use "react16.8.1" and "mobx5.9.4".</p>
  
  <p>My babelrc code: </p>
  
  <pre><code>    "presets": [
          "@babel/preset-env",
          "@babel/preset-react",
  
      ],
      "plugins": [
          "@babel/plugin-transform-runtime",
          "@babel/plugin-transform-object-assign",
          [
             "@babel/plugin-decorators-legacy",
              {
            "legacy": true
              }
          ],
  
  
      ]
  }```
  and my package.json
  
  </code></pre>
  
  <pre><code>{
    "name": "material-dashboard-pro-react",
    "version": "1.5.0",
    "private": true,
    "dependencies": {
      "@material-ui/core": "3.9.2",
      "@material-ui/icons": "3.0.2",
      "axios": "^0.18.0",
      "babel-plugin-transform-decorators-legacy": "^1.3.5",
      "chartist": "0.10.1",
      "history": "4.7.2",
      "mobx": "^5.9.4",
      "mobx-react": "^5.4.3",
      "moment": "2.24.0",
      "moment-jalaali": "^0.8.3",
      "node-sass": "4.11.0",
      "nouislider": "13.1.0",
      "perfect-scrollbar": "1.4.0",
      "rc-pagination": "^1.17.13",
      "react": "16.8.1",
      "react-big-calendar": "0.20.3",
      "react-bootstrap-sweetalert": "4.4.1",
      "react-chartist": "0.13.3",
      "react-datetime": "2.16.3",
      "react-dom": "16.8.1",
      "react-google-maps": "9.4.5",
      "react-hichestan-datetimepicker": "^0.2.12",
      "react-jvectormap": "0.0.6",
      "react-router-dom": "4.3.1",
      "react-scripts": "2.1.5",
      "react-select": "^2.4.2",
      "react-swipeable-views": "0.13.1",
      "react-table": "6.9.2",
      "react-tagsinput": "3.19.0",
      "react-toastify": "^5.0.0",
      "simple-react-modal": "^0.5.1"
    },
    "scripts": {
      "start": "react-scripts start",
      "build": "react-scripts build",
      "test": "react-scripts test --env=jsdom",
      "eject": "react-scripts eject",
      "deploy": "npm run build",
      "lint:check": "eslint . --ext=js,jsx;  exit 0",
      "lint:fix": "eslint . --ext=js,jsx --fix;  exit 0",
    },
    "optionalDependencies": {
      "@types/googlemaps": "3.30.16",
      "@types/markerclustererplus": "2.1.33",
      "ajv": "6.9.1",
      "prettier": "1.16.4"
    },
    "devDependencies": {
      "babel-plugin-transform-decorators-legacy": "^1.3.5",
      "babel-preset-mobx": "^2.0.0",
      "eslint-config-prettier": "4.0.0",
      "eslint-plugin-prettier": "3.0.1"
    },
    "babel": {
      "presets": [
        "react-app",
        "mobx"
      ],
      "plugins": [
        [
          "@babel/plugin-decorators-legacy",
           {
             "legacy": true
           }
        ]
      ]
    },
    "browserslist": [
      "&gt;0.2%",
      "not dead",
      "not ie &lt;= 11",
      "not op_mini all"
    ]
  }
  </code></pre>
  
  <p>I used it before and it was working fine but after upgrading react and mobx, I get this error: "Support for the experimental syntax 'decorators-legacy' isn't currently enabled"</p>