Layer packaging failed but Build still "succeeded" causing outage

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- [X] I have checked to see if my question is addressed in the [FAQ](https://github.com/aws-amplify/amplify-hosting/blob/master/FAQ.md).
- [X] I have [searched for duplicate or closed issues](https://github.com/aws-amplify/amplify-hosting/issues?q=is%3Aissue+).
- [X] I have read the guide for [submitting bug reports](https://github.com/aws-amplify/amplify-hosting/blob/master/CONTRIBUTING.md).
- [X] I have done my best to include a minimal, self-contained set of instructions for consistently reproducing the issue.

### App Id

d2d6ty1wlg8jch

### Region

us-east-1

### Amplify Hosting feature

Backend builds

### Describe the bug

I triggered a build, and an outage occured with one of our Lambdas not able to find packages that are installed via a Lambda Layer.

Looking at the build logs I see this error that seems to be the cause. AWS Amplify console however continued with the build, marked it as successful, and deployed it, causing an outage in our system. We rolled back to previous build and the outage was resolved.

### Expected behavior

The build should have failed, preventing an incorrect deployment.

### Reproduction steps

Seems like there was a temp network issue which caused this.

### Build Settings

```yaml
I don't think this is relevant.
```

### Additional information

_No response_

Start by reviewing the linked issue details and the reported build logs for the Lambda Layer packaging error. Reproduce the failure caused by the temporary network issue if possible, then trace how backend builds interpret that error. Done means a failed layer-packaging step prevents deployment and the build is reported as unsuccessful.

Written by the indexing model from the issue text.