[no-unused-vars] crashes with initialized enums

[targos]

Repro

{
  "rules": {
    "no-unused-vars": "error",
    "typescript/no-unused-vars": "error"
  }
}

export enum Environment {
  development = 'development',
  staging = 'staging',
  production = 'production'
}

Expected Result

No error.

Actual Result

The no-unused-vars core rule's code of ESLint crashes.

Additional Info

Stack trace:

TypeError: Cannot read property 'type' of undefined
    at isForInRef (D:\project\node_modules\eslint\lib\rules\no-unused-vars.js:436:18)
    at variable.references.some (D:\project\node_modules\eslint\lib\rules\no-unused-vars.js:474:13)
    at Array.some (<anonymous>)
    at isUsedVariable (D:\project\node_modules\eslint\lib\rules\no-unused-vars.js:473:34)
    at collectUnusedVariables (D:\project\node_modules\eslint\lib\rules\no-unused-vars.js:613:14)
    at collectUnusedVariables (D:\project\node_modules\eslint\lib\rules\no-unused-vars.js:623:9)
    at collectUnusedVariables (D:\project\node_modules\eslint\lib\rules\no-unused-vars.js:623:9)
    at Program:exit (D:\project\node_modules\eslint\lib\rules\no-unused-vars.js:673:28)
    at listeners.(anonymous function).forEach.listener (D:\project\node_modules\eslint\lib\util\safe-emitter.js:45:58)
    at Array.forEach (<anonymous>)

Versions

package	version
eslint	5.9.0
eslint-plugin-typescript	0.14.0
typescript-eslint-parser	21.0.1
typescript	3.1.6

[bradzacher]

Downgrade your version of typescript-eslint-parser to ^17 and let me know if the issue persists

[armano2]

issue is in parser, and got fixed in eslint/typescript-eslint-parser@491ebca

[targos]

Oh, I see. I just realized that this package relies on a specific version of the typescript parser, sorry.