Check for nullptrs when fuzzing region_deserialize

Bug: oss-fuzz:5629
Change-Id: I1129a6a9a68c69e07ab63e2e2be1c00cf0581962
Reviewed-on: https://skia-review.googlesource.com/102482
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
1 file changed