.eslintrc.json

{
  "env": {
    "browser": true,
    "es6": true,
    "node": true
  },
  "extends": [
    "eslint:recommended",
    "plugin:@typescript-eslint/eslint-recommended",
    "plugin:@typescript-eslint/recommended",
    "plugin:import/recommended",
    "plugin:import/typescript"
  ],
  "parser": "@typescript-eslint/parser",
  "settings": {
    "import/resolver": {
      // The problem is eslint-import-resolver-typescript doesn't support import aliases provided in tsconfig.json without this empty {} non-informative object
      "typescript": {}
    }
  }
}

index.ts

// src/index.ts
import { SomeClass } from '@somedir/SomeClass';

const someClass = new SomeClass()
console.log(someClass)

package.json

{
  "name": "example",
  "productName": "example",
  "version": "1.0.0",
  "main": "src/index.ts",
  "scripts": {
    "lint": "set ESLINT_USE_FLAT_CONFIG=false&& eslint --ext .ts,.tsx ."
  },
  "keywords": [],
  "author": "rarescrap",
  "license": "MIT",
  "devDependencies": {
    "@typescript-eslint/eslint-plugin": "8.50.1",
    "@typescript-eslint/parser": "8.50.1",
    "eslint": "9.39.2",
    "eslint-import-resolver-typescript": "4.4.4",
    "eslint-plugin-import": "2.32.0",
    "typescript": "5.9.3"
  }
}

SomeClass.ts

// src/somedir/SomeClass.ts
export class SomeClass {}

tsconfig.json

{
  "compilerOptions": {
    "allowUnreachableCode": false,
    "allowUnusedLabels": false,
    "alwaysStrict": true,
    "noImplicitAny": true,
    "noImplicitOverride": true,
    "noImplicitReturns": true,
    "noImplicitThis": true,
    "noPropertyAccessFromIndexSignature": true,
    "noUnusedLocals": true,
    "strictBindCallApply": true,
    "strictBuiltinIteratorReturn": true,
    "strictFunctionTypes": true,
    "strictNullChecks": true,
    "baseUrl": ".",
    "module": "commonjs",
    "moduleResolution": "node",
    "paths": {
      "*": ["node_modules/*"],
      "@somedir/*": ["./src/somedir/*"]
    },
    "resolveJsonModule": true,
    "outDir": "dist",
    "removeComments": true,
    "sourceMap": true,
    "allowJs": false,
    "esModuleInterop": true,
    "forceConsistentCasingInFileNames": true,
    "target": "ES6",
    "incremental": true,
    "skipLibCheck": false
  }
}