fix asan error deref-ing null ptr

src/core/SkPath.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBuffer.h"
 #include "SkCubicClipper.h"
 #include "SkErrorInternals.h"
@@ skipping 196 matching lines @@
     }
     return !SkToBool(memcmp(fPathRef->conicWeights(), compare.fPathRef->conicWeights(),
             fPathRef->countWeights() * sizeof(*fPathRef->conicWeights())));
 }
 
 bool SkPath::interpolate(const SkPath& ending, SkScalar weight, SkPath* out) const {
     int verbCount = fPathRef->countVerbs();
     if (verbCount != ending.fPathRef->countVerbs()) {
         return false;
     }
+    if (!verbCount) {
+        return true;
+    }
     out->reset();
     out->addPath(*this);
     fPathRef->interpolate(*ending.fPathRef, weight, out->fPathRef);
     return true;
 }
 
 static inline bool check_edge_against_rect(const SkPoint& p0,
                                            const SkPoint& p1,
                                            const SkRect& rect,
                                            SkPathPriv::FirstDirection dir) {
@@ skipping 2979 matching lines @@
         }
     } while (!done);
     return SkToBool(tangents.count()) ^ isInverse;
 }
 
 int SkPath::ConvertConicToQuads(const SkPoint& p0, const SkPoint& p1, const SkPoint& p2,
                                 SkScalar w, SkPoint pts[], int pow2) {
     const SkConic conic(p0, p1, p2, w);
     return conic.chopIntoQuadsPOW2(pts, pow2);
 }