[cherrypick request for 4.2.0] fix crash on empty virtual actions

[katre]

Cherrypick request for 4.2.0 (#13558).

Fixes #13711 (which is a dupe of #12816).

Original commit:

• 7c92cfc

---

Fixes #12816.

Closes #12819.

PiperOrigin-RevId: 355800567
(cherry picked from commit 7c92cfc)

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[katre]

Overriding CLA since this is a cherrypick of a previous commit that was fine.