settings-endpoints-auth.js

  router.get("/settings", async (ctx) => {
    const session = await Shopify.Utils.loadCurrentSession(ctx.req, ctx.res);
    const shop = session.shop;

    // This shop hasn't been seen yet, go through OAuth to create a session
    if (session === undefined || ACTIVE_SHOPIFY_SHOPS[shop] === undefined) {
      ctx.redirect(`/auth?shop=${shop}`);
      return;
    }

    ctx.status = 200;
  });