This check is useful for preventing a segfault upon usage of this argument.

Change-Id: I3cc77f84d7e3ca2a96ec36a50bddb9c2eadeb62f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1946336Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65373}