[pnm][gridgeometry] Fix bug for caching on

dumux/discretization/porenetwork/gridgeometry.hh

@@ -616,7 +616,7 @@ public:
             LocalIndexType scvfLocalIdx = 0;
             scvfs_[eIdx][0] = SubControlVolumeFace(elementGeometry.center(),
                                                    std::move(unitOuterNormal),
-                                                   throatCrossSectionalArea(this->elementMapper().index(element)),
+                                                   this->throatCrossSectionalArea(this->elementMapper().index(element)),
                                                    scvfLocalIdx++,
                                                    std::vector<LocalIndexType>({0, 1}));
         }