[bug] set a mesh to MeshIO

FileIO/writeMeshToFile.cpp

@@ -29,6 +29,7 @@ void writeMeshToFile(const MeshLib::Mesh &mesh, const std::string &file_name)
 	if (BaseLib::hasFileExtension("msh", file_name))
 	{
 		Legacy::MeshIO meshIO;
+		meshIO.setMesh(&mesh);
 		meshIO.writeToFile(file_name);
 	} else if (BaseLib::hasFileExtension("vtu", file_name)) {
 		FileIO::VtuInterface writer(&mesh);