What this MR does / why does DuMux need it:
This makes sure that an error is thrown when a gmsh file with an unsupported format is used in a multidomain facet coupling simulation. Also, the grid file wasn't properly closed until now.
What this MR does / why does DuMux need it:
This makes sure that an error is thrown when a gmsh file with an unsupported format is used in a multidomain facet coupling simulation. Also, the grid file wasn't properly closed until now.