Error: Missing app.json. See https://docs.expo.io/

[qq471754603]

问题描述
[问题描述：expo build:android Error: Missing app.json. See https://docs.expo.io/]

复现步骤
[复现问题的步骤]
1.在config prod.js文件下添加

// 这里可以贴代码
module.exports = {
  env: {
    NODE_ENV: '"production"'
  },
  defineConstants: {
  },
  weapp: {},
  h5: {},
  rn: {
    appJson: {
      "expo": {
        "name": "myApp",
        "description": "A very interesting project.",
        "slug": "myApp",
        "privacy": "public",
        "sdkVersion": "27.0.0",
        "platforms": ["ios", "android"],
        "version": "1.0.0",
        "orientation": "portrait",
        "updates": {
          "fallbackToCacheTimeout": 0
        },
        "assetBundlePatterns": [
          "**/*"
        ],
        "ios": {
          "bundleIdentifier": "com.fds.myApp"
        },
        "android": {
          "package": "com.fds.myApp"
        }
      }
    }
  }
}
➜  taro git:(master) ✗ taro build --type rn
👽 Taro v1.2.13

开始编译项目 taro
编译  JS        /Users/huxiansheng/Desktop/taro/src/app.js
编译  SCSS      /Users/huxiansheng/Desktop/taro/src/app.scss
生成  生成文件  /Users/huxiansheng/Desktop/taro/.rn_temp/app_styles.js
拷贝  HTML      /Users/huxiansheng/Desktop/taro/src/index.html
编译  JS        /Users/huxiansheng/Desktop/taro/src/components/welcome/index.js
编译  JS        /Users/huxiansheng/Desktop/taro/src/pages/index/index.js
编译  SCSS      /Users/huxiansheng/Desktop/taro/src/pages/index/index.scss
生成  生成文件  /Users/huxiansheng/Desktop/taro/.rn_temp/pages/index/index_styles.js
生成  app.json  /Users/huxiansheng/Desktop/taro/.rn_temp/app.json
生成  package.json  /Users/huxiansheng/Desktop/taro/.rn_temp/package.json
拷贝  crna-entry.js  /Users/huxiansheng/Desktop/taro/.rn_temp/bin/crna-entry.js
编译  编译完成，花费479 ms  

Run expo build:android  or expo build:ios  in .rn_temp/ to building standalone apps
you can visite https://docs.expo.io/versions/latest/distribution/building-standalone-apps for more info
➜  taro git:(master) ✗ expo build:android  
[10:55:14] Error: Missing app.json. See https://docs.expo.io/
[10:55:14] There is an error with your project. See above logs for information.
[10:55:14] Set EXPO_DEBUG=true in your env to view the stack trace.
⠋ Making sure project is set up correctly...%                                                              
➜  taro git:(master) ✗ taro build --type rn
👽 Taro v1.2.13

开始编译项目 taro
编译  JS        /Users/huxiansheng/Desktop/taro/src/app.js
编译  SCSS      /Users/huxiansheng/Desktop/taro/src/app.scss
生成  生成文件  /Users/huxiansheng/Desktop/taro/.rn_temp/app_styles.js
拷贝  HTML      /Users/huxiansheng/Desktop/taro/src/index.html
编译  JS        /Users/huxiansheng/Desktop/taro/src/components/welcome/index.js
编译  JS        /Users/huxiansheng/Desktop/taro/src/pages/index/index.js
编译  SCSS      /Users/huxiansheng/Desktop/taro/src/pages/index/index.scss
生成  生成文件  /Users/huxiansheng/Desktop/taro/.rn_temp/pages/index/index_styles.js
生成  app.json  /Users/huxiansheng/Desktop/taro/.rn_temp/app.json
生成  package.json  /Users/huxiansheng/Desktop/taro/.rn_temp/package.json
拷贝  crna-entry.js  /Users/huxiansheng/Desktop/taro/.rn_temp/bin/crna-entry.js
编译  编译完成，花费477 ms  

Run expo build:android  or expo build:ios  in .rn_temp/ to building standalone apps
you can visite https://docs.expo.io/versions/latest/distribution/building-standalone-apps for more info
➜  taro git:(master) ✗ expo build:android  
[11:00:34] Error: Missing app.json. See https://docs.expo.io/
[11:00:34] There is an error with your project. See above logs for information.
[11:00:34] Set EXPO_DEBUG=true in your env to view the stack trace.
⠋ Making sure project is set up correctly...%                                                              
➜  taro git:(master) ✗ 

期望行为
[生成android包]
报错信息

[Error: Missing app.json. See https://docs.expo.io/
[11:00:34] There is an error with your project. See above logs for information.]

系统信息

Taro v1.2 及以上版本已添加 taro info 命令，方便大家查看系统及依赖信息，运行该命令后将结果贴下面即可。
➜ taro git:(master) ✗ taro info
👽 Taro v1.2.13

Taro CLI 1.2.13 environment info:
System:
OS: macOS 10.14.3
Shell: 5.3 - /bin/zsh
Binaries:
Node: 10.15.1 - /usr/local/bin/node
Yarn: 1.13.0 - /usr/local/bin/yarn
npm: 6.4.1 - /usr/local/bin/npm
npmPackages:
@tarojs/components: 1.2.12 => 1.2.12
@tarojs/plugin-babel: 1.2.12 => 1.2.12
@tarojs/plugin-csso: 1.2.12 => 1.2.12
@tarojs/plugin-sass: 1.2.12 => 1.2.12
@tarojs/plugin-uglifyjs: 1.2.12 => 1.2.12
@tarojs/rn-runner: ^1.2.12 => 1.2.13
@tarojs/router: 1.2.12 => 1.2.12
@tarojs/taro: 1.2.12 => 1.2.12
@tarojs/taro-alipay: 1.2.12 => 1.2.12
@tarojs/taro-h5: 1.2.12 => 1.2.12
@tarojs/taro-swan: 1.2.12 => 1.2.12
@tarojs/taro-tt: 1.2.12 => 1.2.12
@tarojs/taro-weapp: 1.2.12 => 1.2.12
@tarojs/webpack-runner: 1.2.12 => 1.2.12
eslint-config-taro: 1.2.12 => 1.2.12
eslint-plugin-taro: 1.2.12 => 1.2.12
nervjs: ^1.3.9 => 1.3.12

补充信息
[可选]
[app.json配置]

[taro-bot]

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Good luck and happy coding~

[taro-bot]

CC @Pines-Cheng