@skatejs/element should export ES6 class rather than compiled one

[Quasar-Kim]

Bug report

• Skate version: @skatejs/element 0.0.1
• Affected browsers (and versions): Chrome Dev 79.0.3938.0

Current behaviour

Extending Element exported by @skatejs/element triggers following error:

import Element from '@skatejs/element';

class Hello extends Element {
  render() {
    return `
      <span>
        Hello, <slot></slot>!
      </span>
    `;
  }
}
customElements.define('x-hello', Hello);

(An official example introduced here: https://skatejs.netlify.com/docs/element)
Uncaught TypeError: Failed to construct 'HTMLElement': Please use the 'new' operator, this DOM object constructor cannot be called as a function.
Source code on codesandbox. You can see the error on devtools console tab.

Expected behaviour

<x-hello></x-hello> element should render Helllo, !

The issue seems to occur because typescript compiles ES6 class to ES5 syntax.(Related issue)
I tried esnext build in skatejs monorepo which exports ES6 class and it worked.