What is this?
I recommend you to use
tslib-cli because this is a template for tslib-cli.
npm run build
You can run a build fast because it is going to build cjs/esm/browser/d.ts at the same time.
If you have any troubles with paralell build mode, it might be better to try serial build mode.
Paralell build mode is a default setting.
It runs a build in serial. When you use serial build mode, it slows down, but it might be more stable than using paralell build mode.