Overrided component is not rendered

[BenoitClaveau]

The new version of LitElement fails to render overrided component.

class A extends LitElement {
  static get properties() {
        return {
            values: Array,
        }
    }
  render() {
        return html`
            <div>${this.values.map(e => this.renderItem(e))}</div>
        `
    }
   renderItem(e) {
     return null;
   }
}

class B extends A {
  static get properties() {
        return super.properties,
  }
  renderItem(e) {
     return html`<div>TEST</div>`;
   }
}

B do not display a list of

TEST

but render a list of [object Object].

[BenoitClaveau]

There's maybe a link with the issue #712 ?

[BenoitClaveau]

Fixez. I have uninstall/install node_modules