Fix mpi parallelism for mesh smoother

src/mesh/MeshSmoother.cpp

@@ -165,8 +165,6 @@ class MeshSmootherHandler::MeshSmoother
         max_delta_xr[node_id] = max_delta;
       });
 
-    synchronize(max_delta_xr);
-
     NodeValue<Rd> shift_r{connectivity};
 
     parallel_for(
@@ -203,11 +201,7 @@ class MeshSmootherHandler::MeshSmoother
 
     this->_applyBC(shift_r);
 
-#ifndef NDEBUG
-    if (not isSynchronized(shift_r)) {
-      throw UnexpectedError("smoothed mesh coordinates are not synchronized");
-    }
-#endif   // NDEBUG
+    synchronize(shift_r);
 
     return shift_r;
   }