Panel Plugin Development and HMR


I’ve set up a simple panel plugin and I wanted to try out the serve command,
but I always get a “usedComponentDefs[componentName] is undefined” prompt in the panel, when I try to save my changes in the TestField.vue component.
What exactly does it mean and how can I get rid of it? =)
Many thanks in advance!

// index.js
import TestField from "./components/TestField.vue";

window.panel.plugin('kirbyplugin/testfield', {
  fields: {
    testfield: TestField
// TestField.vue
  <div>Some Test</div>

export default {
  name: 'TestField',
// package.json
  "scripts": {
    "dev": "npx -y kirbyup src/index.js --watch",
    "serve": "npx -y kirbyup serve src/index.js",
    "build": "npx -y kirbyup src/index.js"

This is the setup:
kirby 3.8.3
kirbyup 2.1.0

Ok, I switched back to kirby 3.8.2 and it seems to work.