Rollupjs emits '"this" has been rewritten to "undefined"'. How can I address this issue?

Question

Running pnpm install && pnpm build on the simple project below is throwing warning

"this" has been rewritten to "undefined"

Investigating a bit it seems that the code trying to be compiled is coming from tslib. The compiler doesn't know what value this is, so it replaces it with undefined. I'm trying to create a library here that should be run in browser and nodejs. I don't know how to fix this.

---

I can reproduce it with these:

• nodejs: v18.16.0
• pnpm: 8.5.1
• TypeScript: 5.0.4
• rollup: v3.22.0

package.json

{
  "name": "rollup-test",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "build": "rollup -c rollup.config.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "fp-ts": "^2.15.0"
  },
  "devDependencies": {
    "@rollup/plugin-node-resolve": "^15.0.2",
    "@rollup/plugin-typescript": "^11.1.1",
    "tslib": "^2.5.2"
  }
}

rollup.config.js

const typescript = require('@rollup/plugin-typescript');
const { nodeResolve } = require('@rollup/plugin-node-resolve');

module.exports = [
  {
    input: 'src/index.ts',
    output: {
      file: 'dist/index.cjs.js',
      format: 'cjs'
    },
    plugins: [
      nodeResolve(), 
      typescript()
    ]
  }
];

src/index.ts

import * as E from 'fp-ts/Either'

function mylog(str: string) {
  const x = E.right(str)

  if (E.isLeft(x)) {
    console.log(x.left)
  } else {
    console.log(x.right)
  }
}

mylog('hi')

Running pnpm build outputs:

> [email protected] build /Users/theuser/Desktop/rollup-test
> rollup -c rollup.config.js


src/index.ts → dist/index.cjs.js...
(!) "this" has been rewritten to "undefined"
https://rollupjs.org/troubleshooting/#error-this-is-undefined
node_modules/.pnpm/[email protected]/node_modules/fp-ts/es6/function.js
1: var __spreadArray = (this && this.__spreadArray) || function (to, from, pack) {
                        ^
2:     if (pack || arguments.length === 2) for (var i = 0, l = from.length, ar; i < l; i++) {
3:         if (ar || !(i in from)) {
...and 1 other occurrence
node_modules/.pnpm/[email protected]/node_modules/fp-ts/es6/internal.js
1: var __spreadArray = (this && this.__spreadArray) || function (to, from, pack) {
                        ^
2:     if (pack || arguments.length === 2) for (var i = 0, l = from.length, ar; i < l; i++) {
3:         if (ar || !(i in from)) {
...and 1 other occurrence
created dist/index.cjs.js in 369ms