TypeError: Cannot use 'in' operator to search for 'start' in undefined

[EthanShoeDev]

Initial checklist

• I read the support docs
• I read the contributing guide
• I agree to follow the code of conduct
• I searched issues and couldn’t find anything (or linked relevant results below)

Affected packages and versions

"eslint-plugin-mdx": "^3.1.4"

Link to runnable example

https://codesandbox.io/p/devbox/eslint-plugin-mdx-typeerror-remark-lint-xqwl2v

Steps to reproduce

Steps to reproduce:

1. Start with MDX Loader with Next.js codesandbox from issue template.
2. Install eslint and eslint-mdx

npm i -D eslint-plugin-mdx eslint

3. Add eslint config file .eslintrc. Config pulled directly from readme.

{
  "extends": ["plugin:mdx/recommended"],
  "settings": {
    "mdx/code-blocks": true,
    "mdx/language-mapper": {}
  }
}

4. Install remark-lint. reference

npm install vfile-reporter remark remark-preset-lint-consistent remark-preset-lint-recommended remark-lint-list-item-indent --save-dev

5. Setup remark config by adding remarkConfig to package.json. Config pulled directly from remark-lint readme.
6. Remove the trailing new line from pages\index.mdx.
7. Run npx eslint . --ext mdx and result is:

/workspace git:(master) ✗ npx eslint . --ext mdx

Oops! Something went wrong! :(

ESLint: 8.56.0

TypeError: Cannot use 'in' operator to search for 'start' in undefined
Occurred while linting /workspace/pages/index.mdx:1
Rule: "mdx/remark"
    at Program (/workspace/node_modules/eslint-plugin-mdx/lib/rules/remark.js:67:38)
    at ruleErrorHandler (/workspace/node_modules/eslint/lib/linter/linter.js:1076:28)
    at /workspace/node_modules/eslint/lib/linter/safe-emitter.js:45:58
    at Array.forEach (<anonymous>)
    at Object.emit (/workspace/node_modules/eslint/lib/linter/safe-emitter.js:45:38)
    at NodeEventGenerator.applySelector (/workspace/node_modules/eslint/lib/linter/node-event-generator.js:297:26)
    at NodeEventGenerator.applySelectors (/workspace/node_modules/eslint/lib/linter/node-event-generator.js:326:22)
    at NodeEventGenerator.enterNode (/workspace/node_modules/eslint/lib/linter/node-event-generator.js:340:14)
    at CodePathAnalyzer.enterNode (/workspace/node_modules/eslint/lib/linter/code-path-analysis/code-path-analyzer.js:803:23)
    at /workspace/node_modules/eslint/lib/linter/linter.js:1111:32

Expected behavior

eslint should output:

/workspace git:(master) ✗ npx eslint . --ext mdx

/workspace/pages/index.mdx
  1:1  warning  Missing newline character at end of file  remark-lint-final-newline

✖ 1 problem (0 errors, 1 warning)
  0 errors and 1 warning potentially fixable with the `--fix` option.

Actual behavior

eslint outputs:

/workspace git:(master) ✗ npx eslint . --ext mdx

Oops! Something went wrong! :(

ESLint: 8.56.0

TypeError: Cannot use 'in' operator to search for 'start' in undefined
Occurred while linting /workspace/pages/index.mdx:1
Rule: "mdx/remark"
    at Program (/workspace/node_modules/eslint-plugin-mdx/lib/rules/remark.js:67:38)
    at ruleErrorHandler (/workspace/node_modules/eslint/lib/linter/linter.js:1076:28)
    at /workspace/node_modules/eslint/lib/linter/safe-emitter.js:45:58
    at Array.forEach (<anonymous>)
    at Object.emit (/workspace/node_modules/eslint/lib/linter/safe-emitter.js:45:38)
    at NodeEventGenerator.applySelector (/workspace/node_modules/eslint/lib/linter/node-event-generator.js:297:26)
    at NodeEventGenerator.applySelectors (/workspace/node_modules/eslint/lib/linter/node-event-generator.js:326:22)
    at NodeEventGenerator.enterNode (/workspace/node_modules/eslint/lib/linter/node-event-generator.js:340:14)
    at CodePathAnalyzer.enterNode (/workspace/node_modules/eslint/lib/linter/code-path-analysis/code-path-analyzer.js:803:23)
    at /workspace/node_modules/eslint/lib/linter/linter.js:1111:32

Runtime

Node v20

Package manager

npm v9

OS

Linux

Build and bundle tools

Next.js