If the block is unreachable, the interface is not called and the
{try_info} field is not set. Therefore, check it before accessing it.

R=clemensb@chromium.org

Bug: chromium:1188975
Change-Id: Ic6d7d2b7e26b0448143076e25a89c036216e8618
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2767017Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73480}