Check dynamic_cast in TimeDependent

diff --git a/source/numerics/time_dependent.cc b/source/numerics/time_dependent.cc
index a38be6110696436b489fd2a36bc5b2bebb062925..05ecc8a58cc59b38cce9d5b4035bd3ada18522b2 100644 (file)
--- a/source/numerics/time_dependent.cc
+++ b/source/numerics/time_dependent.cc
@@ -1074,7 +1074,7 @@ void TimeStepBase_Tria<dim>::refine_grid (const RefinementData refinement_data)
     {
       Triangulation<dim> *previous_tria
         = dynamic_cast<const TimeStepBase_Tria<dim>*>(previous_timestep)->tria;
-
+      Assert(previous_tria != nullptr, ExcInternalError());
 
       // if we used the dual estimator, we
       // computed the error information on