"Cannot read property 'type' of undefined" after upgrading to 4.14.0

[budarin]

Got the error after upgrading to 4.14.0 on Flow type definitions

TypeError: Cannot read property 'type' of undefined

TypeError: Cannot read property 'type' of undefined
    at isForInRef (..\node_modules\eslint\lib\rules\no-unused-vars.js:410:24)
    at variable.references.some.ref (..\node_modules\eslint\lib\rules\no-unused-vars.js:447:21)
    at Array.some (<anonymous>)
    at isUsedVariable (..\node_modules\eslint\lib\rules\no-unused-vars.js:446:40)
    at collectUnusedVariables (..\node_modules\eslint\lib\rules\no-unused-vars.js:569:26)
    at collectUnusedVariables (..\node_modules\eslint\lib\rules\no-unused-vars.js:576:17)
    at Program:exit (..\node_modules\eslint\lib\rules\no-unused-vars.js:621:36)
    at listeners.(anonymous function).forEach.listener (..\node_modules\eslint\lib\util\safe-emitter.js:47:58)
    at Array.forEach (<anonymous>)
    at Object.emit (..\node_modules\eslint\lib\util\safe-emitter.js:47:38)
    at NodeEventGenerator.applySelector (..\node_modules\eslint\lib\util\node-event-generator.js:251:26)
    at NodeEventGenerator.applySelectors (..\node_modules\eslint\lib\util\node-event-generator.js:280:22)
    at NodeEventGenerator.leaveNode (..\node_modules\eslint\lib\util\node-event-generator.js:303:14)
    at CodePathAnalyzer.leaveNode (..\node_modules\eslint\lib\code-path-analysis\code-path-analyzer.js:630:23)
    at CodePathAnalyzer.overrideLeaveNode (..\node_modules\eslint-plugin-node\lib\rules\process-exit-as-throw.js:127:27)
    at Traverser.leave [as _leave] (..\node_modules\eslint\lib\linter.js:1000:32)
Process finished with exit code -1

[platinumazure]

Are you using babel-eslint? If so, please try upgrading to the latest version of that parser.

[eslint-deprecated]

Hi @budarin, thanks for the issue. It looks like there's not enough information for us to know how to help you.

If you're reporting a bug, please be sure to include:

1. The version of ESLint you are using (run eslint -v)
2. What you did (the source code and ESLint configuration)
3. The actual ESLint output complete with numbers
4. What you expected to happen instead

Requesting a new rule? Please see Proposing a New Rule for instructions.

Requesting a rule change? Please see Proposing a Rule Change for instructions.

If it's something else, please just provide as much additional information as possible. Thanks!

[batazor]

I have the same problem

1. v4.14.0
2. https://github.com/micro-company/react-app/blob/f7763f4f47e636cc32e1ede2a523b665f50a82c3/.eslintrc.yaml

> react-app@0.1.0 lint:fix /home/batazor/micro-company/react-app
> $(npm bin)/eslint --fix ./src

Cannot read property 'type' of undefined
TypeError: Cannot read property 'type' of undefined
    at isForInRef (/home/batazor/micro-company/react-app/node_modules/eslint/lib/rules/no-unused-vars.js:410:24)
    at variable.references.some.ref (/home/batazor/micro-company/react-app/node_modules/eslint/lib/rules/no-unused-vars.js:447:21)
    at Array.some (<anonymous>)
    at isUsedVariable (/home/batazor/micro-company/react-app/node_modules/eslint/lib/rules/no-unused-vars.js:446:40)
    at collectUnusedVariables (/home/batazor/micro-company/react-app/node_modules/eslint/lib/rules/no-unused-vars.js:569:26)
    at Program:exit (/home/batazor/micro-company/react-app/node_modules/eslint/lib/rules/no-unused-vars.js:621:36)
    at listeners.(anonymous function).forEach.listener (/home/batazor/micro-company/react-app/node_modules/eslint/lib/util/safe-emitter.js:47:58)
    at Array.forEach (<anonymous>)
    at Object.emit (/home/batazor/micro-company/react-app/node_modules/eslint/lib/util/safe-emitter.js:47:38)
    at NodeEventGenerator.applySelector (/home/batazor/micro-company/react-app/node_modules/eslint/lib/util/node-event-generator.js:251:26)

4. What you expected to happen instead:

If you disable the no-unused-vars rule, everything works as expected

[platinumazure]

Seems like it might be a duplicate of #9762. Anyone think otherwise?

[batazor]

Yes, it looks like that.
However, the upgrade to `"babel-eslint ":" ^8.1.0 " did not solve the problem

[KevinGrandon]

I'm reproducing this with babel-eslint@8.1.0 and eslint@4.14.0.

[not-an-aardvark]

Could you provide an example of code which causes this issue?

[budarin]

I've installed "babel-eslint": "^8.1.0"

// @flow

import * as React from 'react';

type Temp2Props = {
    count: number,
};

class Temp2 extends React.Component<Temp2Props> {
    shouldComponentUpdate(nextProps) {
        return this.props.count !== nextProps.count;
    }

    render() {
        return <div>{this.props.count}</div>;
    }
}

export default Temp2;

the error has appeared after todays upgrading eslint

[ndelangen]

Can also confirm this is an issue, upgrading caused this:

> $ yarn lint                                                                          [±master ●]
yarn run v1.3.2
$ yarn lint:js . && yarn lint:md .
$ cross-env NODE_ENV=production eslint --cache --cache-location=.cache/eslint --ext .js,.jsx,.json .
Cannot read property 'type' of undefined
TypeError: Cannot read property 'type' of undefined
    at isForInRef (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/rules/no-unused-vars.js:410:24)
    at variable.references.some.ref (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/rules/no-unused-vars.js:447:21)
    at Array.some (<anonymous>)
    at isUsedVariable (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/rules/no-unused-vars.js:446:40)
    at collectUnusedVariables (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/rules/no-unused-vars.js:569:26)
    at collectUnusedVariables (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/rules/no-unused-vars.js:576:17)
    at Program:exit (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/rules/no-unused-vars.js:621:36)
    at listeners.(anonymous function).forEach.listener (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/util/safe-emitter.js:47:58)
    at Array.forEach (<anonymous>)
    at Object.emit (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/util/safe-emitter.js:47:38)
    at NodeEventGenerator.applySelector (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/util/node-event-generator.js:251:26)
    at NodeEventGenerator.applySelectors (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/util/node-event-generator.js:280:22)
    at NodeEventGenerator.leaveNode (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/util/node-event-generator.js:303:14)
    at CodePathAnalyzer.leaveNode (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/code-path-analysis/code-path-analyzer.js:630:23)
    at Traverser.leave [as _leave] (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/linter.js:1000:32)
    at Traverser._traverse (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/util/traverser.js:155:18)
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

Here's our config:

const error = 2;
const warn = 1;
const ignore = 0;

module.exports = {
  root: true,
  extends: ['eslint-config-airbnb', 'plugin:jest/recommended', 'prettier'],
  plugins: ['prettier', 'jest', 'react', 'json'],
  parser: 'babel-eslint',
  parserOptions: {
    sourceType: 'module',
  },
  env: {
    es6: true,
    node: true,
    'jest/globals': true,
  },
  settings: {
    'import/core-modules': ['enzyme'],
  },
  rules: {
    strict: [error, 'never'],
    'prettier/prettier': [
      warn,
      {
        printWidth: 100,
        tabWidth: 2,
        bracketSpacing: true,
        trailingComma: 'es5',
        singleQuote: true,
      },
    ],
    'no-debugger': process.env.NODE_ENV === 'production' ? error : ignore,
    quotes: [warn, 'single', { avoidEscape: true }],
    'class-methods-use-this': ignore,
    'arrow-parens': [warn, 'as-needed'],
    'space-before-function-paren': ignore,
    'import/no-unresolved': error,
    'import/extensions': [
      error,
      {
        js: 'never',
        json: 'always',
      },
    ],
    'import/no-extraneous-dependencies': [
      error,
      {
        devDependencies: [
          'examples/**',
          '**/example/**',
          '*.js',
          '**/*.test.js',
          '**/*.stories.js',
          '**/scripts/*.js',
          '**/stories/**/*.js',
          '**/__tests__/**/*.js',
        ],
        peerDependencies: true,
      },
    ],
    'import/prefer-default-export': ignore,
    'react/jsx-wrap-multilines': ignore,
    'react/jsx-indent': ignore,
    'react/jsx-indent-props': ignore,
    'react/jsx-closing-bracket-location': ignore,
    'react/jsx-uses-react': error,
    'react/jsx-uses-vars': error,
    'react/react-in-jsx-scope': error,
    'react/jsx-filename-extension': [
      warn,
      {
        extensions: ['.js', '.jsx'],
      },
    ],
    'jsx-a11y/accessible-emoji': ignore,
    'jsx-a11y/href-no-hash': ignore,
    'jsx-a11y/label-has-for': ignore,
    'jsx-a11y/click-events-have-key-events': error,
    'jsx-a11y/anchor-is-valid': [warn, { aspects: ['invalidHref'] }],
    'react/no-unescaped-entities': ignore,
  },
};

I can verify it's a problem related to babel-eslint, when I disable:

  parser: 'babel-eslint',
  parserOptions: {
    sourceType: 'module',
  },

I can run eslint again. though I get parse errors obviously.

I've run eslint with debug enabled, and copied the final few lines:

  eslint:cli-engine Processing /Users/dev/Projects/GitHub/storybook/core/examples/official-storybook/components/FlowTypeButton.js +16ms
  eslint:cli-engine Linting /Users/dev/Projects/GitHub/storybook/core/examples/official-storybook/components/FlowTypeButton.js +0ms
  eslint:config Constructing config file hierarchy for /Users/dev/Projects/GitHub/storybook/core/examples/official-storybook/components +0ms
  eslint:config Using .eslintrc and package.json files +0ms
  eslint:config Loading /Users/dev/Projects/GitHub/storybook/core/examples/official-storybook/package.json +0ms
  eslint:config-file Loading package.json config file: /Users/dev/Projects/GitHub/storybook/core/examples/official-storybook/package.json +0ms
  eslint:config-file Loading JSON config file: /Users/dev/Projects/GitHub/storybook/core/examples/official-storybook/package.json +0ms
  eslint:config Using config from cache +0ms
  eslint:linter Linting code for /Users/dev/Projects/GitHub/storybook/core/examples/official-storybook/components/FlowTypeButton.js (pass 1) +0ms
  eslint:traverser Unknown node type "TypeAlias": Estimated visitor keys ["type","start","end","loc","range","id","typeParameters","right"] +328ms
  eslint:traverser Unknown node type "ObjectTypeAnnotation": Estimated visitor keys ["type","start","end","loc","range","callProperties","properties","indexers","exact"] +0ms
  eslint:traverser Unknown node type "ObjectTypeProperty": Estimated visitor keys ["type","start","end","loc","range","static","kind","value","variance","optional"] +0ms
  eslint:traverser Unknown node type "StringTypeAnnotation": Estimated visitor keys ["type","start","end","loc","range"] +0ms
  eslint:traverser Unknown node type "ObjectTypeProperty": Estimated visitor keys ["type","start","end","loc","range","static","kind","value","variance","optional"] +0ms
  eslint:traverser Unknown node type "GenericTypeAnnotation": Estimated visitor keys ["type","start","end","loc","range","typeParameters","id"] +0ms
  eslint:traverser Unknown node type "ObjectTypeProperty": Estimated visitor keys ["type","start","end","loc","range","static","kind","value","variance","optional"] +0ms
  eslint:traverser Unknown node type "BooleanTypeAnnotation": Estimated visitor keys ["type","start","end","loc","range"] +0ms
Cannot read property 'type' of undefined
TypeError: Cannot read property 'type' of undefined
    at isForInRef (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/rules/no-unused-vars.js:410:24)
    at variable.references.some.ref (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/rules/no-unused-vars.js:447:21)
    at Array.some (<anonymous>)
    at isUsedVariable (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/rules/no-unused-vars.js:446:40)
    at collectUnusedVariables (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/rules/no-unused-vars.js:569:26)
    at collectUnusedVariables (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/rules/no-unused-vars.js:576:17)
    at Program:exit (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/rules/no-unused-vars.js:621:36)
    at listeners.(anonymous function).forEach.listener (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/util/safe-emitter.js:47:58)
    at Array.forEach (<anonymous>)
    at Object.emit (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/util/safe-emitter.js:47:38)
    at NodeEventGenerator.applySelector (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/util/node-event-generator.js:251:26)
    at NodeEventGenerator.applySelectors (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/util/node-event-generator.js:280:22)
    at NodeEventGenerator.leaveNode (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/util/node-event-generator.js:303:14)
    at CodePathAnalyzer.leaveNode (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/code-path-analysis/code-path-analyzer.js:630:23)
    at Traverser.leave [as _leave] (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/linter.js:1000:32)
    at Traverser._traverse (/Users/dev/Projects/GitHub/storybook/core/node_modules/eslint/lib/util/traverser.js:155:18)
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

[not-an-aardvark]

@budarin I can't seem to reproduce this issue with the code that you've provided. I'm using the following code in foo.js (the file you provided):

foo.js

// @flow

import * as React from 'react';

type Temp2Props = {
    count: number,
};

class Temp2 extends React.Component<Temp2Props> {
    shouldComponentUpdate(nextProps) {
        return this.props.count !== nextProps.count;
    }

    render() {
        return <div>{this.props.count}</div>;
    }
}

export default Temp2;

---

With the following config file:

.eslintrc.yml

parser: babel-eslint
rules:
  no-unused-vars: error

---

And I'm running the following from the command line:

$ rm -rf node_modules/
$ npm install eslint@4.14.0 babel-eslint@8.1.0
$ node_modules/.bin/eslint foo.js

When I do this, no errors are reported and no crashes occur.

I don't doubt that some problem exists based on the number of people commenting on this issue, but I wasn't able to reproduce a problem with your example code.

[batazor]

@not-an-aardvark
My error occurs when I check the directory, but not when I check the files separately

[not-an-aardvark]

Are you sure that the file you pasted is the file where the crash is occurring? (To find the file where the crash is occurring, try running ESLint with the --debug flag to see which file is currently getting linted when the crash happens.)