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

Had to add the dependencies manually, even when it gave a warning of incompatibility, because the npm-force-resolutions solution did not work for me.

1. First, I had to add the following dependencies to package.json (dependencies because I'm using create-react-app, which I have never seen to use devDependencies):

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

2. Then, I do rm -rf node_modules/ so I can have a clean install of npm stuff.

3. Next, install everything: npm install.

4. Check that you have the correct version: npm ls @typescript-eslint/eslint-plugin. It said UNMET PEER DEPENDENCY but I had to ignore it because otherwise I could not get this working.

5. npm start to make sure the create-react-app now works.

I'd advice going for the npm-force-resolutions solution first, but if it fails try this one.

Oh, and one extra note:

This entire disaster was because I did something like this:

interface SomeInterface {
  someBoolean: boolean,
  someList: number[],
  someTuple: [string, string]  // <-- THIS is the problem
}

If I removed that commented line, the code would compile without issues. I kept it that way because I had already made my code to work like that, but if you just avoid having a tuple inside the interface (didn't matter if it had labels or not), you can potentially avoid all this hassle.