TypeError in Firefox when using a particular element two times

[gitaarik]

Description

When you have an element like this:

class MyElement extends LitElement {

  render() {
    const cool = html`cool!`;
    return html`
      <div>${cool}</div>
    `;
  }

}

And you use this element two times, then you get a TypeError: this.endNode is null in your Firefox console. If you don't use the const but just put the string cool! at the place of ${cool} it doesn't happen. It works in Chrome.

Live Demo

Demo: https://understood-humor.glitch.me/
Source code: https://glitch.com/edit/#!/understood-humor

Steps to Reproduce

1. Create an element like mentioned above
2. Use this element two times on a page
3. Test in Firefox

Expected Results

You should get two times the text "cool!" underneath each other.

Actual Results

In Firefox the text "cool!" only appears one time. The first element is rendered, after that you get an error in the console TypeError: this.endNode is null.

Browsers Affected

• Chrome
• Firefox

Versions

• lit-element: v0.6.0
• webcomponents: v2.1.2

[sorvell]

The issue is actually with the latest release of lit-html. Tracked as lit/lit#505.

[gitaarik]

Nice! Thanks 😃 👍