🐛 Fix nil dereference when DescribeDhcpOptions call returns an error

[dlipovetsky]

What type of PR is this?
/kind bug

What this PR does / why we need it:

This fixes a nil dereference that causes the controller to panic.

The PR has two commits. The first commit adds a (failing) test that reproduces the issue. The second commit fixes the issue.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

Checklist:

• squashed commits
• includes documentation
• includes emoji in title
• adds unit tests
• adds or updates e2e tests

Release note:

NONE

[faiq]

/lgtm

im not sure what the lint error is about. thanks for adding unit tests too!

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 154ea1edcd84dbdbc0a733d218c38a67985dbf87

[dlipovetsky]

/lgtm

im not sure what the lint error is about. thanks for adding unit tests too!

Last time lint check passed was https://github.com/kubernetes-sigs/cluster-api-provider-aws/actions/runs/19889397833/job/57004172122#step:6:10. It's been failing with the same error since:

Error: build process: clone golangci-lint: git clone --branch v2.1.0 --single-branch --depth 1 -c advice.detachedHead=false -q https://github.com/golangci/golangci-lint.git: exit status 128
Failed executing command with error: build process: clone golangci-lint: git clone --branch v2.1.0 --single-branch --depth 1 -c advice.detachedHead=false -q https://github.com/golangci/golangci-lint.git: exit status 128
make: *** [Makefile:310: /home/runner/work/cluster-api-provider-aws/cluster-api-provider-aws/hack/tools/bin/golangci-lint-kube-api-linter] Error 3

[dlipovetsky]

I've identified the lint problem. It's golangci/golangci-lint#5641. We bumped Go version ahead of the Go version used to build golangci-lint in #5782.

We'll need to bump golangci-lint to one built with Go 1.24.x. I'll file a PR.

(At least this is my working theory--I'll need to confirm it 😅 )

[damdo]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: damdo

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[damdo]

/hold

Until linitng is fixed