It's my fault for not including my removal of it in the changelog. I've just updated it.
It was removed because it's identical to fb.GetFocusItem which is used much more often.
Also, I think your usage was incorrect.
var save_focus_handle = plman.GetPlaylistFocusItemHandle(p.list.playlist);
The optional argument is force which defaults to true when omitted.
Original docs:
IFbMetadbHandle GetPlaylistFocusItemHandle(force);
Original docs for GetFocusItem
// force: if this parameter is set to false, GetFocusItem() will only look for the focus item, otherwise,
// if the focus item not found, find the first item of the active playlist.
IFbMetadbHandle GetFocusItem(force = true);
You can see here where I removed it from my own mod of JSplaylist...
https://github.com/19379/jsplaylist-mod/com...08dbcede7a16f47