It took me a while to figure out how to set up everything to run the
fuzzer locally. These improved error messages would have helped to find
errors earlier.

R=machenbach@chromium.org

Bug: chromium:1142437
Change-Id: I414de0a8448cd81fdbf999cc7c3c8cf9394354f6
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2543397
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71239}