fix pathops fuzz

recent fuzz hang fix returned nullptr
and could cause crash

R=kjlubick@google.com

Bug: skia:8481
Change-Id: Ie8291077aa5f4e4b878f204b2a9ff71d2c1f7b94
Reviewed-on: https://skia-review.googlesource.com/c/163480
Commit-Queue: Cary Clark <caryclark@skia.org>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
Auto-Submit: Cary Clark <caryclark@skia.org>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
1 file changed