fix: handle nil ParseableType from GVKParser

[leoluz]

fix: #18020

Checklist:

• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this does not need to be in the release notes.
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[crenshaw-dev]

@leoluz which releases should we cherry-pick this to?

[leoluz]

/cherry-pick release-2.11

[gcp-cherry-pick-bot]

Cherry-pick failed with Merge error 62d983807661019f83e27e0bee373ed587a7f57c into temp-cherry-pick-9472ab-release-2.11

[blakepettersson]

/cherry-pick release-2.10

[gcp-cherry-pick-bot]

Cherry-pick failed with Merge error 62d983807661019f83e27e0bee373ed587a7f57c into temp-cherry-pick-9472ab-release-2.10

[blakepettersson]

Gah, I missed that gitops-engine has a bunch of client-go upgrades which makes backporting this fix to 2.10 impossible.

[crenshaw-dev]

Ugh. More reasons to merge gitops-engine back into the argo-cd repo.