"What is bare module import?" You may ask.

import { ref } from 'vue';

This is it. You are imporing from 'vue', instead of './vue/...'
In native browser, this is not supported. You get this error.
So vite shim it. It generate a cache when it's first loaded.

Problem is if this package is owned by you and you link it with npm link. It's not visible in the package user. You have to disable the cache like this.

export default {
  optimizeDeps: {
    exclude: [

Here's I'm developing an ui lib juju-ui, and it's changed quite often.