fix some fuzz

src/pathops/SkPathOpsCommon.cpp

Index: src/pathops/SkPathOpsCommon.cpp
diff --git a/src/pathops/SkPathOpsCommon.cpp b/src/pathops/SkPathOpsCommon.cpp
index b0a24a709440dc4c0ca6d9923d2bfd2993fb746a..b4049bc5d9bd30f2502319e345a997fe49fdf12c 100644
--- a/src/pathops/SkPathOpsCommon.cpp
+++ b/src/pathops/SkPathOpsCommon.cpp
@@ -302,7 +302,9 @@ bool HandleCoincidence(SkOpContourHead* contourList, SkOpCoincidence* coincidenc
         if (!coincidence->addExpanded(DEBUG_COIN_ONLY_PARAMS())) {
             return false;
         }
-        coincidence->mark(DEBUG_PHASE_ONLY_PARAMS(kWalking));
+        if (!coincidence->mark(DEBUG_PHASE_ONLY_PARAMS(kWalking))) {
+            return false;
+        }
     } else {
         (void) coincidence->expand(DEBUG_COIN_ONLY_PARAMS());
     }