/usr/local/home/ is also not guaranteed to exist - you should instead retreive the content of $HOME variable and use that directory.
I have updated the opk with this change. I'm still puzzled though, $HOME is /usr/local/home so why does it matter?
$HOME is /usr/local/home today, but that might not be the case in the future. For example, we could allow multiple user profiles per Zero, so you can share the device with other people without getting your settings and high scores polluted. In that case, every user profile would have its own separate home directory and $HOME would point to the home directory of the active user.
Another reason to use $HOME is that it will work on any Unix-like system, so it makes your code more portable.