error: Missing or invalid options at ShopifyToken

[fancydev18]

Hello there!

I think I did all the proper app setup. When installing in a dev store via Shopify actions, I get this error:

info: Checking for valid session: undefined
[0] info: Authenticating shop undefined
[0] GET /api/products 302 13.086 ms - 63
[0] info: Checking for valid session: my-test1.myshopify.com
[0] info: Authenticating shop my-test1.myshopify.com
[0] error:  message=Missing or invalid options, stack=Error: Missing or invalid options
[0]     at new ShopifyToken (/create-shopify-app/node_modules/shopify-token/index.js:48:13)
[0]     at getShopifyToken (/create-shopify-app/compiled/webpack:/server/routes/shopify.js:32:5)
[0]     at authenticate (/create-shopify-app/compiled/webpack:/server/routes/shopify.js:63:26)
[0]     at authMiddleware (/create-shopify-app/compiled/webpack:/server/routes/shopify.js:228:7)
[0]     at Layer.handle [as handle_request] (/create-shopify-app/node_modules/express/lib/router/layer.js:95:5)
[0]     at trim_prefix (/create-shopify-app/node_modules/express/lib/router/index.js:317:13)

Didn't see this in other issues. What would be the cause?

Also, trying to figure out how to serve react apps embedded in Shopify. Normally, one would access react app at http://localhost:3001
For Shopify though, I see this setup:

app.use((err, req, res, next) => {
  logger.error(err);
  const status = err.status || 500;
  res.status(status);
  res.render(`${status}`, {
    message: err.message,
    error: isDebug && err.stack,
    APP_URL
  });
});

There is no "200" view though. How does it work, without having to build/transpile the app everytime to serve it inside Shopify?

Thanks!