esbuild code-splitting

add.ts

import { log } from './shared';
export default (a: number, b: number): number => {
  log();
  return a + b;
}

index.ts

export { default as add } from './add';
export { default as subtract } from './subtract';

package.json

{
  "name": "esbuild-spltting-issue",
  "version": "1.0.0",
  "main": "dist/index.js",
  "type": "module",
  "exports": {
    ".": {
      "import": "./dist/index.js"
    },
    "./add": {
      "import": "./dist/add.js"
    },
    "./subtract": {
      "import": "./dist/subtract.js"
    }
  },
  "scripts": {
    "build": "esbuild --bundle --splitting --format=esm --outdir=dist index.ts add.ts subtract.ts"
  },
  "dependencies": {
    "esbuild": "^0.8.0"
  }
}

shared.ts

export const log = (): void => console.log('I am shared code!');

subtract.ts

import { log } from './shared';
export default (a: number, b: number): number => {
  log();
  return a - b;
}