chore: fix-bug-in-computePointAtDistanceThreshold

Author: mdorford

web-bundle/src/main/java/com/graphhopper/resources/BufferResource.java

@@ -484,6 +484,14 @@ private PointList computePointAtDistanceThreshold(BufferFeature startFeature, Do
         EdgeIteratorState finalState = graph.getEdgeIteratorState(endFeature.getEdge(), Integer.MIN_VALUE);
         PointList pointList = finalState.fetchWayGeometry(FetchMode.PILLAR_ONLY);
 
+        // It is possible that the finalState.fetchWayGeometry(FetchMode.xxxx) would
+        // only contain TOWER points and not PILLAR points.
+        // When this happens, filtering by FetchMode.PILLAR_ONLY will return an empty
+        // PointList.
+        if (pointList.size() == 0) {
+            return new PointList();
+        }
+
         // When the buffer is only as wide as a single edge, truncate one half of the
         // segment
         if (startFeature.getEdge().equals(endFeature.getEdge())) {