🐛 fix(nodegroup): add nil pointer check for nodegroup version

[nueavv]

Added a check to ensure that the nodegroup version is not nil before dereferencing it. This prevents potential runtime panics due to nil pointer dereference.

What type of PR is this?

/kind bug

What this PR does / why we need it:

This PR adds a nil pointer check for the nodegroup version in the reconcileNodegroupVersion function. This prevents potential runtime panics caused by dereferencing a nil pointer when the nodegroup version is not set.

Which issue(s) this PR fixes: Fixes #5018

Special notes for your reviewer:

This change is essential to ensure the stability of the reconcileNodegroupVersion function by preventing nil pointer dereference issues.

Checklist:

• [x] squashed commits
• [ ] includes documentation
• [ ] includes emojis
• [x] adds unit tests
• [ ] adds or updates e2e tests

Release note:

Fix nil pointer dereference in reconcileNodegroupVersion by adding a check for nodegroup version.

[k8s-ci-robot]

Adding the "do-not-merge/release-note-label-needed" label because no release-note block was detected, please follow our release note process to remove it.

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[linux-foundation-easycla[bot]]

• :white_check_mark:login: nueavv / (df089ef9f628db4b64c03488f38e4e3375871ef8)

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[k8s-ci-robot]

Hi @nueavv. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes-sigs/prow](https://github.com/kubernetes-sigs/prow/issues/new?title=Prow%20issue:) repository.

[nueavv]

I have built and tested the updated code, and it seems that the panic no longer occurs. Here are the updated logs. It seems the panic issue has been resolved

I0613 04:01:44.064508       1 reconcile.go:39] "Reconciling kube-proxy DaemonSet in cluster" controller="awsmanagedcontrolplane" controllerGroup="controlplane.cluster.x-k8s.io" controllerKind="AWSManagedControlPlane" AWSManagedControlPlane="capi-managed-cluster/[REDACTED]" namespace="capi-managed-cluster" name="[REDACTED]" reconcileID="a4ce3943-5cdb-4467-aba9-18a759fd6cb2" awsManagedControlPlane="capi-managed-cluster/[REDACTED]" cluster="capi-managed-cluster/[REDACTED]"
I0613 04:01:44.065051       1 reconcile.go:39] "Reconciling aws-iam-authenticator configuration" controller="awsmanagedcontrolplane" controllerGroup="controlplane.cluster.x-k8s.io" controllerKind="AWSManagedControlPlane" AWSManagedControlPlane="capi-managed-cluster/[REDACTED]" namespace="capi-managed-cluster" name="[REDACTED]" reconcileID="a4ce3943-5cdb-4467-aba9-18a759fd6cb2" awsManagedControlPlane="capi-managed-cluster/[REDACTED]" cluster="capi-managed-cluster/[REDACTED]"
E0613 04:01:44.386103       1 controller.go:329] "Reconciler error" err="failed to reconcile machine pool for AWSManagedMachinePool capi-managed-cluster/[REDACTED]: failed to reconcile nodegroup version: nodegroup version is nil" controller="awsmanagedmachinepool" controllerGroup="infrastructure.cluster.x-k8s.io" controllerKind="AWSManagedMachinePool" AWSManagedMachinePool="capi-managed-cluster/[REDACTED]" namespace="capi-managed-cluster" name="[REDACTED]" reconcileID="3e0c724f-236b-4262-9c06-e22f83b0eacd"
I0613 04:01:44.386891       1 awsmanagedmachinepool_controller.go:200] "Reconciling AWSManagedMachinePool"
I0613 04:01:44.387068       1 launchtemplate.go:73] "checking for existing launch template"
I0613 04:01:44.439150       1 reconcile.go:90] "Reconciled aws-iam-authenticator configuration" controller="awsmanagedcontrolplane" controllerGroup="controlplane.cluster.x-k8s.io" controllerKind="AWSManagedControlPlane" AWSManagedControlPlane="capi-managed-cluster/[REDACTED]" namespace="capi-managed-cluster" name="[REDACTED]" reconcileID="a4ce3943-5cdb-4467-aba9-18a759fd6cb2" awsManagedControlPlane="capi-managed-cluster/[REDACTED]" cluster="[REDACTED]"
E0613 04:01:44.858183       1 controller.go:329] "Reconciler error" err="failed to reconcile machine pool for AWSManagedMachinePool capi-managed-cluster/[REDACTED]: failed to reconcile nodegroup version: nodegroup version is nil" controller="awsmanagedmachinepool" controllerGroup="infrastructure.cluster.x-k8s.io" controllerKind="AWSManagedMachinePool" AWSManagedMachinePool="capi-managed-cluster/[REDACTED]" namespace="capi-managed-cluster" name="[REDACTED]" reconcileID="9bec8c74-79d0-4b39-bd40-607a5d899630"
I0613 04:01:44.859110       1 awsmanagedmachinepool_controller.go:200] "Reconciling AWSManagedMachinePool"
I0613 04:01:44.859320       1 launchtemplate.go:73] "checking for existing launch template"
E0613 04:01:45.297763       1 controller.go:329] "Reconciler error" err="failed to reconcile machine pool for AWSManagedMachinePool capi-managed-cluster/[REDACTED]: failed to reconcile nodegroup version: nodegroup version is nil" controller="awsmanagedmachinepool" controllerGroup="infrastructure.cluster.x-k8s.io" controllerKind="AWSManagedMachinePool" AWSManagedMachinePool="capi-managed-cluster/[REDACTED]" namespace="capi-managed-cluster" name="[REDACTED]" reconcileID="91a7cb58-d6f8-4e8f-aa06-62acce826b74"
I0613 04:01:45.298635       1 awsmanagedmachinepool_controller.go:200] "Reconciling AWSManagedMachinePool"
I0613 04:01:45.298821       1 launchtemplate.go:73] "checking for existing launch template"
E0613 04:01:45.743834       1 controller.go:329] "Reconciler error" err="failed to reconcile machine pool for AWSManagedMachinePool capi-managed-cluster/[REDACTED]: failed to reconcile nodegroup version: nodegroup version is nil" controller="awsmanagedmachinepool" controllerGroup="infrastructure.cluster.x-k8s.io" controllerKind="AWSManagedMachinePool" AWSManagedMachinePool="capi-managed-cluster/[REDACTED]" namespace="capi-managed-cluster" name="[REDACTED]" reconcileID="ef2c12c6-5c2b-4553-a62e-f69ce561d6d9"
I0613 04:01:45.744691       1 awsmanagedmachinepool_controller.go:200] "Reconciling AWSManagedMachinePool"
I0613 04:01:45.744882       1 launchtemplate.go:73] "checking for existing launch template"
E0613 04:01:46.178107       1 controller.go:329] "Reconciler error" err="failed to reconcile machine pool for AWSManagedMachinePool capi-managed-cluster/[REDACTED]: failed to reconcile nodegroup version: nodegroup version is nil" controller="awsmanagedmachinepool" controllerGroup="infrastructure.cluster.x-k8s.io" controllerKind="AWSManagedMachinePool" AWSManagedMachinePool="capi-managed-cluster/[REDACTED]" namespace="capi-managed-cluster" name="[REDACTED]" reconcileID="a0c1977f-6e74-499e-805c-147fe74d8e39"
I0613 04:01:46.178945       1 awsmanagedmachinepool_controller.go:200] "Reconciling AWSManagedMachinePool"
I0613 04:01:46.179150       1 launchtemplate.go:73] "checking for existing launch template"

[richardcase]

/ok-to-test