Fix labeled select enter key error

[momesgin]

Summary

Fixes #17951

Occurred changes and/or fixed issues

• Fixed TypeError: Cannot read properties of undefined (reading 'value') thrown when pressing Enter in a LabeledSelect dropdown.

Technical notes summary

When a search yields no results the selected option is undefined. Added null guards in vue-select-overrides.js and LabeledSelect.vue to handle this safely. Unit tests added to cover the undefined case and normal selection behaviour.

Areas or cases that should be tested

1. Open any LabeledSelect dropdown (e.g. Namespace selector, any form select field).
2. Type in the search box until there's no option found.
3. Press Enter

no error should appear in the console and the dropdown should behave normally.

Areas which could experience regressions

• Any form that uses LabeledSelect — especially those with searchable/filterable option lists.

Screenshot/Video

entrkey.mov

Checklist

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• The PR has a Milestone
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• The PR has a reviewer assigned
• The PR has automated tests or clear instructions for manual tests and the linked issue has appropriate QA labels, or tests are not needed
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• The PR has considered, and if applicable tested with, the three Global Roles Admin, Standard User and User Base

[github-actions]

🔄 Auto-Retry Failed Run

The Tests workflow failed for the commits below and has been automatically retried.
Follow up on a retried run through its link if needed.

Commit	Workflow run	Retried at
079b307	31084698757	2026-08-06 09:09 UTC
b7da1b0	31121673430	2026-08-06 17:21 UTC
1115bca	31192698351	2026-08-07 16:03 UTC
ecae3f3	31221758359	2026-08-07 22:23 UTC

[codyrancher]

I found one issue and I believe it's related to this section here. Things that shouldn't be selectable are now selectable via the keyboard (not the mouse)

pr18684-stale-pointer.mp4

[momesgin]

The recording is very interesting! I'm not able to type in the authentication field with or without my change. Could you give me the exact steps to get to that point?

[codyrancher]

Before the steps in the video just create 5 basic http secrets, you have to overflow the menu before it's taggable. I confirmed that it's only selectable with these changes, master doesn't show this. If you still can't repro we can hop on a quick call.

[momesgin]

oh right! I didn't have enough items on the list, thanks for catching this will address it.

[momesgin]

done, @codyrancher thanks for the review and helping to reproduce the problem

[codyrancher]

It looks like your fix does work and it improves things so I don't want to hold this PR up.

While testing your fix I did notice one more related issue but it's present in master as well so it wasn't introduced by this change. If you'd like to fix it here feel free but I'm fine if you'd just like to merge this.

If you type in the labels starting worth the exact wording they're selectable via pressing enter as well.

enter-select.mp4

[momesgin]

It looks like your fix does work and it improves things so I don't want to hold this PR up.

While testing your fix I did notice one more related issue but it's present in master as well so it wasn't introduced by this change. If you'd like to fix it here feel free but I'm fine if you'd just like to merge this.

If you type in the labels starting worth the exact wording they're selectable via pressing enter as well.

enter-select.mp4

I don't think we'd need a new issue for this, I'll work on it