Module build failed: TypeError: Property right of AssignmentExpression expected node to be of a type ["Expression"] but instead got null at Array.map (native)

[BigFaceMaster]

Choose one: is this a bug report or feature request?

Input Code

var your => (code) => here;

Babel/Babylon Configuration (.babelrc, package.json, cli command)

{
  "your": { "config": "here" }
}

Expected Behavior

Current Behavior

Possible Solution

Context

Your Environment

software	version(s)
Babel
Babylon
node
npm
Operating System

[babel-bot]

Hey @leejay1992! We really appreciate you taking the time to report an issue. The collaborators
on this project attempt to help as many people as possible, but we're a limited number of volunteers,
so it's possible this won't be addressed swiftly.

If you need any help, or just have general Babel or JavaScript questions, we have a vibrant Slack
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[nicolo-ribaudo]

Please fill the issue template

[babel-bot]

Hi @leejay1992! A maintainer of the project has notified me that you're missing
some information we'll need to replicate this issue.

Please understand that we receive a high volume of issues, and there are only a limited number
of volunteers that help maintain this project. The easier it is for us to decipher an issue with the info provided,
the more likely it is that we'll be able to help.

Please make sure you have the following information documented in this ticket:

1. Your Babel configuration (typically in the form of a .babelrc)
2. The current (incorrect) behavior you're seeing
3. The behavior you expect
4. A short, self-contained example

Please provide either a link to the problem via the repl, or if the repl is insufficient,
a new and minimal repository with instructions on how to build/replicate the issue.

[cburbank]

@leejay1992 I started seeing this error after upgrading my project to babel beta 46 (was previously on beta 44), and it seems it may indicate some conflict between babel plugins. In my case I was able to resolve it by removing babel-plugin-transform-decorators-legacy and adding "decoratorsLegacy": true to the @babel/env @babel/stage-0 preset options.

[BingoBinBingo]

Good Nice

[somonek]

@cburbank's solution didn't work for me, but I was able to solve it by having the decorators plugin like this:

{
  "presets": [
    "@babel/preset-react",
    ["@babel/preset-env", {
      "targets": {
        "browsers": ["last 2 versions"]
      }
    }]
  ],
  "plugins": [
    ["@babel/plugin-proposal-decorators", {
      "legacy": true
    }],
    "react-hot-loader/babel",
    "@babel/plugin-proposal-class-properties",
    "@babel/plugin-proposal-object-rest-spread",
    "@babel/plugin-syntax-export-extensions",
    "transform-function-bind"
  ]
}

[capaj]

@somonek thanks for your comment-I've also resolved this issue by replacing the plugin:

[hyochan]

I am suffering from this issue in react-native@0.56 any idea? Related to issue.

[TitanKing]

@dooboolab Did you manage to find a solution for this?

[hyochan]

@TitanKing No. I've wasted a day to solve this problem. What's funny is, it works ok when I use typescript. I feel like babel@7 is facing many issues currently.

[TitanKing]

@dooboolab Yeah I cannot spend days trying to get past this. Oh well, reverting is the only option then I guess. Thanks for the feedback.

[mCodex]

I've also tried:

  "resolutions": {
    "babel-core": "^7.0.0-bridge.0"
  },

in my package.json and then:

rm -rf node_modules/ yarn.lock && yarn

but still doesn't work :/

[dimapaloskin]

Looks like this bug related with this commit: b8dcd6f
which totally renamed callee to expression

The quick fix:
https://github.com/babel/babel/blob/master/packages/babel-plugin-proposal-decorators/src/transformer-legacy.js#L49

const expression = decorator.expression; -> const expression = decorator.expression || decorator.callee

[nicolo-ribaudo]

@dimapaloskin That is only a problem when you are using different versions of the various packages.

[xuqinggang]

Note: please ensure babel plugin package version is consistent!

[nicolo-ribaudo]

You shouldn't use ^ in beta versions: they could get out of sync

[rknell]

@TitanKing @dooboolab I found it, I found it, I found it!

Righto - so metro bundler in react native 0.56 only supports babel 7 beta v47

Which means its actually due to a version mismatch, just not one in your package.json. I solved this by looking at the missing peer dependencies when running yarn - So if this changes in the future and causes the same issue, check the yarn output.

So what I did was

package.json

  "devDependencies": {
    "@babel/core": "7.0.0-beta.47",
    "@babel/plugin-proposal-decorators": "7.0.0-beta.47",
    "@babel/plugin-transform-runtime": "7.0.0-beta.47",
    "@babel/runtime": "7.0.0-beta.47",
    ...

.babelrc

{
  "presets": [
    "react-native"
  ],
  "plugins": [
    [
      "@babel/plugin-proposal-decorators",
      {
        "legacy": true
      }
    ],
    [
      "@babel/plugin-transform-runtime",
      {
        "helpers": true,
        "polyfill": false,
        "regenerator": false
      }
    ]
  ]
}

Note: I did need to remove @babel/parser as it was first introduced in beta 48

[hyochan]

@rknell Thanks. My app is running now. However, there is another problem left for me which is jest. It works fine when I downgrade to react-native@0.55.4 but throws error message in 0.56.

 Requires Babel "^7.0.0-0", but was loaded with "6.26.3". If you are sure you have a compatible version of @babel/core, it is likely that something in your build process is loading the wrong version. Inspect the stack trace of this error to look for the first entry that doesn't mention "@babel/core" or "babel-core" to see what is calling Babel.

If you also face the build error in configuring jest, look up issue which solved my problem.
The important part is changing jest configuration in package.json.

"^.+\\.js$": "<rootDir>/node_modules/react-native/jest/preprocessor.js",

Thank you by the way with the decorator issue.

[hvaoc]

I got the same error when adding Mobx support to my react native project.

Changes suggested by @dooboolab above fixed this error for me.

Am using "react-native": "^0.56.0".

[mehulmpt]

Yes. Downgrading to 0.47 version fixes the problem. I'm keeping dependencies as:

  "@babel/core": "7.0.0-beta.47",
   "@babel/plugin-proposal-optional-chaining": "7.0.0-beta.47",
   "@babel/preset-env": "7.0.0-beta.47",
   "@babel/preset-stage-2": "7.0.0-beta.47",

before babel 7 is stable for react native

[existentialism]

@mehulmpt just to clarify: “babel 7 is stable for react native”... it is, it’s just that all your @babel/* dependencies need to fixed to matching versions, and since RN is currently using beta47, you must too.

[mehulmpt]

Yeah, I meant to say "before we can do semver for babel 7 packages for react native" @existentialism

[schumannd]

@somonek s answer solved it for me:

before:

{
  "presets": ["react-native"],
  "plugins": [
    "transform-decorators-legacy"
  ]
}

after:

{
  "presets": ["react-native"],
  "plugins": [
    ["@babel/plugin-proposal-decorators", {
      "legacy": true
    }],
  ]
}

[rborn]

@rknell could you please share the whole package.json / .babelrc ?
I'm losing my mind here trying to make mobx run with RN 0.56 in release mode 😹

Thank you 🤗

[hvaoc]

@rborn - Can't let folks suffer...

This is what I am having in my project to make Mobx work with React Native 0.56, hope this helps you all.

.babelrc

{
  "presets": [
    "react-native"
  ],
  "plugins": [
    [
      "@babel/plugin-proposal-decorators",
      {
        "legacy": true
      }
    ]
  ]
}

package.json

{
  "name": "MyProject",
  "version": "0.0.1",
  "dependencies": {
    "@babel/plugin-proposal-decorators": "7.0.0-beta.47",
    "@babel/runtime": "7.0.0-beta.47",
    "add": "^2.0.6",
    "axios": "^0.18.0",
    "deep-object-diff": "^1.1.0",
    "fast-json-patch": "^2.0.7",
    "flat": "^4.1.0",
    "lodash": "^4.17.10",
    "mobx": "^5.0.3",
    "mobx-react": "^5.2.3",
    "react": "16.4.1",
    "react-dom": "^16.4.1",
    "react-native": "^0.56.0",
    "react-native-code-push": "^5.4.1",
    "react-native-country-picker-modal": "^0.6.2",
    "react-native-firebase": "^4.3.7",
    "react-native-form": "^2.1.2",
    "react-native-gifted-chat": "^0.4.3",
    "react-native-lightbox": "git://github.com/oblador/react-native-lightbox.git#0a37652",
    "react-native-linear-gradient": "^2.4.0",
    "react-native-loading-spinner-overlay": "^0.5.2",
    "react-native-segmented-control-tab": "^3.2.2",
    "react-native-text-input-enhance": "^1.0.11",
    "react-native-typography": "^1.3.0",
    "react-native-vector-icons": "^4.6.0",
    "react-navigation": "^2.6.2",
    "react-navigation-header-buttons": "^2.0.1",
    "styled-components": "^3.3.3",
    "uuid": "^3.3.2",
    "yarn": "^1.9.4"
  },
  "devDependencies": {
    "babel-jest": "23.4.0",
    "babel-preset-react-native": "^5",
    "flow-bin": "^0.76.0",
    "jest": "^23.4.1",
    "jsc-android": "^224109.0.0",
    "react-native-cli": "^2.0.1",
    "react-native-rename": "^2.2.2",
    "react-test-renderer": "16.4.1"
  },
  "jest": {
    "preset": "react-native"
  }
}

[rborn]

@hvaoc I fixed like this:
you need to have .babelrc split in dev/production like here oblador/react-native-vector-icons#801 (comment)

Alsop keep @babel/* vesions to 7.0.0-beta.47

Thanks a lot for your help 🤗

[xtuc]

Since no information were provided in the issue initially, I'm going to close this. Please feel free to re-open a new issue.