add regularity check for hessian

dune/tectonic/data-structures/friction/localfriction.hh

@@ -136,7 +136,8 @@ class WrappedScalarFriction : public LocalFriction<dimension> {
     }*/
     auto tangential_x = removeNormal(x);
     const double xnorm = tangential_x.two_norm();
-    if (xnorm <= 0.0)
+
+    if (std::isinf(func_.regularity(xnorm)) or xnorm<=0.0)
       return;
 
     VectorType y = tangential_x;