GET /_next/webpack-hmr 404

I ran npx serve . at .../aws_sumerian/packages/amazon-sumerian-hosts-three

I receive error:

```
HTTP 10/11/2023 11:06:51 AM ::1 Returned 404 in 0 ms
HTTP 10/11/2023 11:06:51 AM ::1 GET /_next/webpack-hmr
```

I did the [AWS-Infrastructure-Setup.md](https://github.com/aws-samples/amazon-sumerian-hosts/tree/mainline2.0/AWS-Infrastructure-Setup.md) step, where I added: const cognitoIdentityPoolId = '....';
module.exports = cognitoIdentityPoolId; in .../aws_sumerian/demo-credentials.js

Start by reviewing how packages/amazon-sumerian-hosts-three is served with npx serve . and compare that behavior with the AWS-Infrastructure-Setup.md instructions and demo-credentials.js. Determine whether the GET /_next/webpack-hmr request is expected for this package and document or correct the serving setup so the reported 404 has a clear resolution.

Written by the indexing model from the issue text.