Replace std::exit by std::terminate to ease debugging

src/mesh/ConnectivityComputer.cpp

@@ -24,7 +24,7 @@ computeConnectivityMatrix(const ConnectivityType& connectivity,
   } else {
     perr() << "unable to compute connectivity "
               << itemName(item_type) << " -> " << itemName(child_item_type) << '\n';
-    std::exit(0);
+    std::terminate();
   }
 
   return item_to_child_item_matrix;