Cannot get LIT to work with my custom lovelace card

Not sure what the issue is. In my card, I have the following import:

import {
LitElement,
html,
css,
} from “https://unpkg.com/[email protected]/lit-element.js?module”;

When I load from chrome, I get the following error:

log-message.ts:36 GET http://harbr2:8123/unknown/src/scoped-custom-element-registry.js 404 (Not Found)

The card itself is loading… I’m confused, because other custom lovelace cards work fine. Any thoughts?