No mutable exports error

[NullDivision]

I get the following error when running version 2.2.0:

Cannot read property 'kind' of null
TypeError: Cannot read property 'kind' of null
    at checkDeclaration (/home/nulldivision/Projects/node_modules/eslint-plugin-import/lib/rules/no-mutable-exports.js:10:24)
    at checkDeclarationsInScope (/home/nulldivision/Projects/node_modules/eslint-plugin-import/lib/rules/no-mutable-exports.js:24:15)
    at EventEmitter.handleExportNamed (/home/nulldivision/Projects/node_modules/eslint-plugin-import/lib/rules/no-mutable-exports.js:46:11)
    at emitOne (events.js:101:20)
    at EventEmitter.emit (events.js:188:7)
    at NodeEventGenerator.enterNode (/home/nulldivision/Projects/node_modules/eslint/lib/util/node-event-generator.js:40:22)
    at CodePathAnalyzer.enterNode (/home/nulldivision/Projects/node_modules/eslint/lib/code-path-analysis/code-path-analyzer.js:608:23)
    at CommentEventGenerator.enterNode (/home/nulldivision/Projects/node_modules/eslint/lib/util/comment-event-generator.js:97:23)
    at Controller.enter (/home/nulldivision/Projects/node_modules/eslint/lib/eslint.js:927:36)
    at Controller.__execute (/home/nulldivision/Projects/node_modules/eslint/node_modules/estraverse/estraverse.js:397:31)

[ljharb]

Can you provide the code it's erroring out on?

[NullDivision]

Sadly I cannot. The codebase is fairly big and more importantly proprietary.

Based on the error I'm thinking if it wouldn't make sense to have handle
the case by checking if node has an actual value. I'm not sure what the
case might be where def might not have a parent (or what def actually
is).

[jfmengels]

It would be really helpful to have a MVP / example of the error. Even if your codebase is big and proprietary, you could do the following to help us fix this (while maintaining the privacy of your codebase):

• Try to pinpoint the file(s) that cause the error: Run eslint on only some of the folders, and dive deeper into the folders where you keep having this crash.
• Once you have the file, comment/remove some of the code until you are left with a short code example
• Change the code in order to hide any sensible information (change variable names, remove most logic from the code, ...)

In the case of this rule, it's very likely that you'll end up with a very short code example which will not betray any sensitive information about your project :)

If you find the time to do this, that'd be awesome!

[benmosher]

I'm pretty unfamiliar with EScope, but @NullDivision is right that def.parent is optional and thus is worth checking.

I goofed around with a few weird syntaxes (undeclared / unbound identifiers) and couldn't reproduce the error, but I suspect the change in bfdc2bb should resolve this.

Would still love a repro case, if you can manage it. 😅

[chrisnojima]

@benmosher Hi, I have a way to reproduce this w/ v2.2.0. In this commit I work around the issue. keybase/client@199bb2a If left as the commit before then it'll give the above error.

[rwe]

@benmosher Is it possible to get a minor bump release for this? The referenced commit fixes it.

I believe it's caused by using the syntax-flow Babel plugin and exporting type definitions. For reference, here's an example of a failing node:

Definition {
  type: 'Variable',
  name:
   Node {
     type: 'Identifier',
     start: 17,
     end: 19,
     loc: SourceLocation { start: [Object], end: [Object], identifierName: 'ID' },
     name: 'ID',
     range: [ 17, 19 ],
     _babelType: 'Identifier',
     parent:
      Node {
        type: 'TypeAlias',
        start: 12,
        end: 29,
        loc: [Object],
        id: [Circular],
        typeParameters: null,
        right: [Object],
        leadingComments: [Object],
        range: [Object],
        _babelType: 'TypeAlias',
        parent: [Object] } },
  node:
   Node {
     type: 'TypeAlias',
     start: 12,
     end: 29,
     loc: SourceLocation { start: [Object], end: [Object] },
     id:
      Node {
        type: 'Identifier',
        start: 17,
        end: 19,
        loc: [Object],
        name: 'ID',
        range: [Object],
        _babelType: 'Identifier',
        parent: [Circular] },
     typeParameters: null,
     right:
      Node {
        type: 'StringTypeAnnotation',
        start: 22,
        end: 28,
        loc: [Object],
        range: [Object],
        _babelType: 'StringTypeAnnotation',
        parent: [Circular] },
     leadingComments: [ [Object] ],
     range: [ 12, 29 ],
     _babelType: 'TypeAlias',
     parent:
      Node {
        type: 'Program',
        start: 0,
        end: 983,
        loc: [Object],
        comments: [Object],
        tokens: [Object],
        range: [Object],
        sourceType: 'module',
        directives: undefined,
        body: [Object],
        parent: null } },
  parent: null,
  index: null,
  kind: null }
Cannot read property 'kind' of null
TypeError: Cannot read property 'kind' of null
    at checkDeclaration (node_modules/eslint-plugin-import/lib/rules/no-mutable-exports.js:10:24)
    at checkDeclarationsInScope (node_modules/eslint-plugin-import/lib/rules/no-mutable-exports.js:25:15)
    at EventEmitter.handleExportNamed (node_modules/eslint-plugin-import/lib/rules/no-mutable-exports.js:47:11)
    at emitOne (events.js:101:20)
    at EventEmitter.emit (events.js:188:7)
    at NodeEventGenerator.enterNode (node_modules/eslint/lib/util/node-event-generator.js:39:22)
    at CodePathAnalyzer.enterNode (node_modules/eslint/lib/code-path-analysis/code-path-analyzer.js:607:23)
    at CommentEventGenerator.enterNode (node_modules/eslint/lib/util/comment-event-generator.js:97:23)
    at Controller.enter (node_modules/eslint/lib/eslint.js:928:36)
    at Controller.__execute (node_modules/estraverse/estraverse.js:397:31)

Caused by code similar to:

type Foo = {};
type Bar = {};

export type {
  Foo,
  Bar,
};

[nickydonna]

I having this issue with a file I use for flow types

File:

//@flow
type Activity = { id: string, name: string };
type DescriptionType = { name: string, text: string, remarks: string[] };
type DescriptionsType = { en: DescriptionType, es: DescriptionType };
type RecurrentDate = { times: Date[] };

type EditableTour = {
    props: Object
}

export type {
  Activity,
  DescriptionType,
  DescriptionsType,
  RecurrentDate,
  EditableTour,
};

.eslintrc

{
  "parser": "babel-eslint",
  "extends": "airbnb",
  "globals": {
    "document": true,
    "window": true,
    "process": true,
    "API_URL": true,
    "React$Element": true,
    "SyntheticEvent": true,
    "SyntheticInputEvent": true,
    "FormData": true,
    "fetch": true,
    "File": true
  },
  "rules": {
    "import/extensions": 0,
    "import/no-extraneous-dependencies": 0,
    "import/no-unresolved": 0,
    "react/jsx-filename-extension": 0,
    "linebreak-style": 0,
    "react/no-did-mount-set-state": 0,
    "spaced-comment": 0,
    "camelcase": 0,
    "react/no-multi-comp": 0
  }
}

please help!

[hazeledmands]

I've got a PR (#835) that adds a test for this :)