Fixed crash

source/ubl-settings-usergroups.c

@@ -1170,8 +1170,8 @@ void on_system_parameter_changed(GtkWidget *, ubl_settings_usergroups_group_crea
 	char *final_str = yon_char_unite(
 		yon_char_return_if_exist(non_unique,""),
 		!yon_char_is_empty(non_unique)?" ":"",
-		yon_char_return_if_exist(gsystem,"")
-	);
+		yon_char_return_if_exist(gsystem,""),
+		NULL);
 	gtk_entry_set_text(GTK_ENTRY(window->groupExtraOptionsEntry),final_str);
 	free(final_str);
 }