The non-deleted sprites are not really an issue since your operating system takes care of freeing up the memory once the game closes. Also, the whole point of killing the program with keyboard shortcuts like Ctrl+Alt+Del, Alt+F4 and Alt+X is that it allows you to quit whenever the game freezes (usually because of a scripting error). In such cases an on_close_game event would never be run anyway. A better solution to the problem would be simply make the engine only generate the error log when running in debug mode. There's no reason to worry end-users with something that's not even an issue.