Duplicate type name error from model extending another model with visibility

[bterlson]

Best described by example (playground

import "@typespec/http";

using TypeSpec.Http;
@service({
  title: "Widget Service",
  version: "1.0.0",
})
namespace DemoService;

model Widget {
  @visibility("read", "update")
  @path
  id: string;

  weight: int32;
  color: "red" | "blue";
}

model CreatedWidget extends Widget {

}

@route("/widgets")
@tag("Widgets")
interface Widgets {

  // This works
  // @route("create1")
  // @post create1(widget: Widget): Widget;

  // this doesn't (also the error is not the best)
  // but if you have both of these, it works again
  @route("create2")
  @post create2(widget: Widget): CreatedWidget;
}