I’ve just had a go with this; the first JS code snippet needed to be updated a wee bit.
This now needs to go in the JS tab of a Theme Component (or Theme) instead:
import { apiInitializer } from "discourse/lib/api";
import { iconNode } from "discourse-common/lib/icon-library";
export default apiInitializer("0.11.1", (api) => {
api.decorateWidget("post-notice:before", () => {
return iconNode("heart");
});
});
I didn’t look at using an image instead sorry.