fetch-clang-format: better error checking

Change-Id: Idc0e984275056128301d4f1ae66aa6ace67b05d5
Reviewed-on: https://skia-review.googlesource.com/98322
Reviewed-by: Hal Canary <halcanary@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
1 file changed