title: Cannot build main.jsbundle file either manually or automatically
body: <p>I am trying to buil the /ios/main.jsbundle file manually in the command line (MacOSX Mojave 10.14.4 (18E226)) having ./index.js as entry file. But I don't succeed.</p>
  
  <p>Then I use this file in Xcode (Version 10.2.1 (10E1001)).</p>
  
  <p>I am building main.jsbundle with the following commands from the root folder:</p>
  
  <pre><code>$ react-native bundle --entry-file ./index.js --platform ios --dev false --bundle-output main.jsbundle
  </code></pre>
  
  <p>OR</p>
  
  <pre><code>$ react-native bundle --entry-file ./index.js --platform its --bundle-output main.jsbundle
  </code></pre>
  
  <p>this appears with the --verbose flag:</p>
  
  <pre><code>Loading dependency graph, done.
  error index.js: Plugin/Preset files are not allowed to export objects, only functions. In /Users/me/MyApp/node_modules/babel-preset-react-native-stage-0/decorator-support.js
  debug Error: Plugin/Preset files are not allowed to export objects, only functions. In /Users/me/MyApp/node_modules/babel-preset-react-native-stage-0/decorator-support.js
      at createDescriptor (/Users/me/MyApp/node_modules/@babel/core/lib/config/config-descriptors.js:178:11)
      at /Users/me/MyApp/node_modules/@babel/core/lib/config/config-descriptors.js:109:50
      at Array.map (&lt;anonymous&gt;)
      at createDescriptors (/Users/me/MyApp/node_modules/@babel/core/lib/config/config-descriptors.js:109:29)
      at createPresetDescriptors (/Users/me/MyApp/node_modules/@babel/core/lib/config/config-descriptors.js:101:10)
      at presets (/Users/me/MyApp/node_modules/@babel/core/lib/config/config-descriptors.js:47:19)
      at mergeChainOpts (/Users/me/MyApp/node_modules/@babel/core/lib/config/config-chain.js:320:26)
      at /Users/me/MyApp/node_modules/@babel/core/lib/config/config-chain.js:283:7
      at mergeExtendsChain (/Users/me/MyApp/node_modules/@babel/core/lib/config/config-chain.js:299:21)
  </code></pre>
  
  <p>I tried to find a similar question, but nothing.</p>
  
  <p>I have also tried to clean the cache, clear watchman watches, killing the metro bundler, relaunch Xcode, update brew, npm.</p>
  
  <p>These are my files:</p>
  
  <ul>
  <li>package.json file:</li>
  </ul>
  
  <pre><code>{
    "name": "MyApp",
    "version": "0.2.0",
    "private": true,
    "devDependencies": {
      "@babel/core": "^7.4.4",
      "@babel/plugin-proposal-decorators": "^7.4.4",
      "@babel/preset-env": "^7.4.4",
      "@babel/preset-react": "^7.0.0",
      "babel-preset-react-native-stage-0": "^1.0.1",
      "flow-bin": "^0.77.0",
      "flow-remove-types": "^1.2.3",
      "jest": "^24.8.0",
      "jest-react-native": "^18.0.0",
      "react-test-renderer": "16.3.1"
    },
    "scripts": {
      "start": "react-native start",
      "android": "react-native run-android",
      "ios": "react-native run-ios",
      "test": "jest",
      "build": "flow-remove-types --all --pretty ./flow_src/ -d ./src",
      "flow": "flow"
    },
    "jest": {
      "preset": "react-native",
      "setupFiles": [
        "&lt;rootDir&gt;/test/config/setup.js"
      ],
      "testPathIgnorePatterns": [
        "/test/config/setup",
        "/test/config/assetsTransformer"
      ],
      "moduleNameMapper": {
        "\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$": "&lt;rootDir&gt;/test/config/assetsTransformer.js",
        "\\.(css|less)$": "&lt;rootDir&gt;/test/config/assetsTransformer.js"
      }
    },
    "dependencies": {
      "@types/react": "^16.8.17",
      "@types/react-native": "^0.57.53",
      "@types/react-navigation": "^3.0.7",
      "assert": "^1.5.0",
      "babel-preset-react-native": "^5.0.2",
      "braces": "^2.3.2",
      "moment": "^2.24.0",
      "react": "^16.8.6",
      "react-native": "^0.59.8",
      "react-native-collapsible": "^0.9.0",
      "react-native-dialog": "^5.6.0",
      "react-native-doc-viewer": "^2.7.8",
      "react-native-elements": "^0.19.1",
      "react-native-fetch-blob": "^0.10.8",
      "react-native-fs": "^2.13.3",
      "react-native-orientation": "^3.1.3",
      "react-native-pdf": "^3.0.17",
      "react-native-picker-select": "^4.4.0",
      "react-native-progress": "^3.6.0",
      "react-native-render-html": "^3.10.0",
      "react-native-timeago": "^0.4.0",
      "react-native-vector-icons": "^4.6.0",
      "react-native-video": "^3.2.1",
      "react-navigation": "^2.18.3",
      "yallist": "^3.0.3"
    }
  }
  
  </code></pre>
  
  <p>*.babelrc file:</p>
  
  <pre><code>{
    "presets": [
      "babel-preset-react-native-stage-0/decorator-support"
    ],
    "env": {
      "development": {
        "plugins": [
          "transform-react-jsx-source"
        ]
      }
    }
  }
  </code></pre>
  
  <ul>
  <li>System Info</li>
  </ul>
  
  <pre><code>info 
    React Native Environment Info:
      System:
        OS: macOS 10.14.4
        CPU: (8) x64 Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz
        Memory: 20.87 GB / 32.00 GB
        Shell: 3.2.57 - /bin/bash
      Binaries:
        Node: 12.1.0 - /usr/local/bin/node
        npm: 6.9.0 - /usr/local/bin/npm
        Watchman: 4.9.0 - /usr/local/bin/watchman
      SDKs:
        iOS SDK:
          Platforms: iOS 12.2, macOS 10.14, tvOS 12.2, watchOS 5.2
      IDEs:
        Xcode: 10.2.1/10E1001 - /usr/bin/xcodebuild
      npmPackages:
        react: ^16.8.6 =&gt; 16.8.6 
        react-native: ^0.59.8 =&gt; 0.59.8 
      npmGlobalPackages:
        create-react-native-app: 2.0.2
        react-native-cli: 2.0.1 
  </code></pre>