remove compiler warning

[[Imported from SVN: r3750]]

common/geometrytype.hh

@@ -7,6 +7,8 @@
     \brief A unique label for each type of element that can occur in a grid
  */
 
+#include <dune/common/exceptions.hh>
+
 namespace Dune {
 
   /** \brief Enum that declares identifiers for different geometry types.
@@ -99,6 +101,7 @@ namespace Dune {
       case pyramid : return Dune::pyramid;
       case prism :   return Dune::prism;
       }
+      DUNE_THROW(Exception, "Non-existing BasicType found!");
     }
 
     /** @name Setup Methods */