kbld with flag --json swallows error

**What steps did you take:**
I have config.yaml
```
apiVersion: apps/v1
kind: Deployment
metadata:
name: kbld-nginx
spec:
selector:
matchLabels:
app: kbld-nginx
template:
metadata:
labels:
app: kbld-nginx
spec:
containers:
- name: my-app
image: nginxix
```
And it is throwing error when run kbld command without `--json` flag:
```
$ kbld -f nginx/config.yml
kbld: Error:
- Resolving image 'nginxix': GET https://index.docker.io/v2/library/nginxix/manifests/latest: UNAUTHORIZED: authentication required; [map[Action:pull Class: Name:library/nginxix Type:repository]]
```

While it will exit without printing any error message or any log if will run with flag `--json`

**What happened:**
When we run kbld command with flag `--json` it is exiting without printing any error message or any log in case of failure.

**What did you expect:**
When we run kbld command with flag `--json` it should print error message in case of failure.

**Anything else you would like to add:**
[Additional information that will assist in solving the issue.]

**Environment:**

- kbld version (use `kbld --version`):
- Docker registry used (e.g. `Docker HUB`):
- OS (e.g. from `/etc/os-release`):

If building images using `docker`:
- Docker CLI Version (e.g. `docker version`)

If building images using `buildkit`:
- Buildkit version (e.g. `kubectl buildkit version`):
- Kubernetes version (e.g. `kubectl version`):

If building images using `pack`
- Pack Version (e.g. `pack version`):

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Reproduce the failure with the provided nginx/config.yml and the kbld command using --json, then trace the CLI entry point that handles image-resolution errors and JSON output. Done means the command reports the registry error when --json is enabled, while preserving the existing non-JSON behavior.

Written by the indexing model from the issue text.