Error deploying action Returned HTTP 503 (Service Unavailable) --> "Response Missing Error Message."

In the setup where an action `index.js` and its dependencies is zipped with :

```
const rtLib = require('@adobe/aio-lib-runtime')

rtLib.utils.zip(
'dist/application/actions/pages-temp',
'dist/application/actions/pages.zip'
)
```

adding `const { Core } = require('@adobe/aio-sdk');` to the action and deploying it to runtime with `aio app deploy --no-web-assets --no-build` fails with the following error:

```
› Error: PUT https://adobeioruntime.net/api/v1/namespaces/mynamespace/actions/actions/pages Returned HTTP 503 (Service Unavailable) --> "Response Missing Error Message."
```

Start with the action's index.js, the @adobe/aio-sdk Core require, and the aio-lib-runtime zip invocation. Reproduce the failure with aio app deploy --no-web-assets --no-build; done means determining why deployment returns HTTP 503 and making the deployment succeed or expose a meaningful error.

Written by the indexing model from the issue text.