Line 0: Parsing error: Cannot read property 'map' of undefined

Question

Currently starting up the server on my client side, the error above is what I have been getting. I am using Typescript, React, ESlint. I can\'t seem to go forward since th

Answer 1

This error occurs because react-scripts has a direct dependency on the 2.xx range of @typescript-eslint/parser and @typescript-eslint/eslint-plugin.

You can fix this by adding a resolutions field to your package.json as follows:

"resolutions": {
  "**/@typescript-eslint/eslint-plugin": "^4.1.1",
  "**/@typescript-eslint/parser": "^4.1.1"
}

NPM users: add the resolutions field above to your package.json but use npx npm-force-resolutions to update package versions in package-lock.json.

Yarn users: you don't need to do anything else. See selective dependency resolutions for more info.

NOTE: if you're using a monorepo/Yarn workspaces, the resolutions field must be in the top-level package.json.

NOTE: yarn add and yarn upgrade-interactive don't respect the resolutions field and they can generate a yarn.lock file with incorrect versions as a result. Watch out.