README.md

commonjs re-export of js + deceleration emit = crash!

run yarn tsc4p1 = Crash!!

run yarn tsc4p0 = "private name error is expected"

lib.js

/**
 * @param {string} a
 */
function bar(a) {
    return a + a;
}

class SomeClass {
    a() {
        return 1;
    }
}

module.exports = {
    bar,
    SomeClass
}

main.js

const { SomeClass } = require('./lib');

module.exports = {
    SomeClass,
}

package.json

{
  "name": "ya-emit-types-from-js-issue",
  "version": "1.0.0",
  "author": "Bnaya Peretz",
  "license": "MIT",
  "private": "true",
  "scripts": {
    "tsc4p0": "npx -p typescript@4.0.x tsc",
    "tsc4p1": "npx -p typescript@4.1.0-dev.20201021 tsc"  
  }
}

tsconfig.json

{
  "compilerOptions": {
    "target": "ES2020",
    "module": "commonjs",
    "lib": ["ES2020"],
    "allowJs": true,
    "checkJs": true,
    "declaration": true,
    "declarationMap": true,
    "sourceMap": true,
    "outDir": "./dist",
    "rootDir": "./",
    "composite": true,
    "tsBuildInfoFile": "./dist/tsconfig.tsbuildinfo",
    "isolatedModules": true,
    "strict": true,
    "types": [],  
    "esModuleInterop": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true
  },
  "include": ["main.js", "lib.js"],
  "exclude": ["dist"]
}