[cpp] Fix handling of degenerate clipping polygons, closes #2579

spine-cpp/spine-cpp/src/spine/SkeletonClipping.cpp

@@ -363,6 +363,10 @@ bool SkeletonClipping::clip(float x1, float y1, float x2, float y2, float x3, fl
 	} else
 		originalOutput->setSize(originalOutput->size() - 2, 0);
 
+    if (originalOutput->size() < 6) {
+        originalOutput->clear();
+        return false;
+    }
 	return clipped;
 }