crash on malformed package.json

[jacekkopecky]

If package.json is malformed, eslint fails by crashing. This is relevant because then in Atom, every file that is to be checked by eslint is marked as invalid.

Tell us about your environment

• ESLint Version: 4.19.1
• Node Version: 9.8.0
• npm Version: 6.0.1

What parser (default, Babel-ESLint, etc.) are you using?

default

Please show your full configuration:

Configuration

original package.json so I can npm i eslint:

{
  "name": "test",
  "version": "0.1.0",
  "description": "test eslint",
  "main": "app.js",
  "scripts": {
    "lint": "eslint ."
  },
  "author": "Jacek Kopecky <jacek@jacek.cz>",
  "engines": {
    "node": ">=8.7.0"
  },
  "devDependencies": {
    "eslint": "^4.19.1"
  }
}

No .eslintrc or anything like that.

What did you do? Please include the actual source code causing the issue, as well as the command that you used to run ESLint.

I was editing package.json and introduced a syntax error - the usual extra comma (near the end of the file below).

{
  "name": "test",
  "version": "0.1.0",
  "description": "test eslint",
  "main": "app.js",
  "scripts": {
    "lint": "eslint ."
  },
  "author": "Jacek Kopecky <jacek@jacek.cz>",
  "engines": {
    "node": ">=8.7.0"
  },
  "devDependencies": {
    "eslint": "^4.19.1",
  }
}

Then I want to lint the project:

eslint .

What did you expect to happen?

Eslint should either fail gracefully with a warning because it can't parse package.json, or it assumes there's nothing in package.json of interest to eslint (which is correct) and proceeds to check the directory, which is otherwise empty so eslint succeeds quietly. If eslint fails, its output should clearly blame package.json in the normal »this file has a linting error« format.

What actually happened? Please include the actual, raw output from ESLint.

Crash.

Unexpected token } in JSON at position 275
SyntaxError: Unexpected token } in JSON at position 275
    at JSON.parse (<anonymous>)
    at new IgnoredPaths (/Users/kopeckyj/tmp/eslint/node_modules/eslint/lib/ignored-paths.js:176:55)
    at lodash.memoize.optionsObj (/Users/kopeckyj/tmp/eslint/node_modules/eslint/lib/util/glob-util.js:115:13)
    at memoized (/Users/kopeckyj/tmp/eslint/node_modules/lodash/lodash.js:10551:27)
    at globPatterns.forEach.pattern (/Users/kopeckyj/tmp/eslint/node_modules/eslint/lib/util/glob-util.js:175:34)
    at Array.forEach (<anonymous>)
    at Object.listFilesToProcess (/Users/kopeckyj/tmp/eslint/node_modules/eslint/lib/util/glob-util.js:158:18)
    at CLIEngine.executeOnFiles (/Users/kopeckyj/tmp/eslint/node_modules/eslint/lib/cli-engine.js:518:35)
    at Object.execute (/Users/kopeckyj/tmp/eslint/node_modules/eslint/lib/cli.js:189:111)
    at Object.<anonymous> (/Users/kopeckyj/tmp/eslint/node_modules/eslint/bin/eslint.js:74:28)

[platinumazure]

Hi @jacekkopecky, thanks for the issue. I agree this is a bug, and at the very least we should have a more sensible error message.

Feel free to submit a PR if you wish 😄

[jacekkopecky]

Hi, I'd love to have a stab at it but I'm too busy with the day job until July easily.

[g-plane]

Should the error stack be outputed?

[not-an-aardvark]

I think it would be nice to output the error message, but outputting the stack is probably not necessary.

So the output could look something like this:

Failed to parse config file at /foo/bar/.eslintrc.json:

SyntaxError: Unexpected token } in JSON at position 275

[g-plane]

How about removing the stack info before throwing error?

[not-an-aardvark]

We already have code in place for pretty-printing error messages by adding a messageTemplate property to the thrown error -- if an error has a messageTemplate, then a corresponding message from the messages/ folder is printed rather than a stack trace.

For example, see:

eslint/lib/config.js

Lines 255 to 263 in a812845

	const noConfigError = new Error("No ESLint configuration found.");
	noConfigError.messageTemplate = "no-config-found";
	noConfigError.messageData = {
	directory,
	filesExamined: localConfigFiles
	};
	throw noConfigError;

edit: the message templates are in the messages/ folder, not the templates/ folder.

[g-plane]

Thanks! I'll check it.