DFPlayer Mini MP3 number of files in a folder

The Mini MP3 player has the capability of holding 6,000 MP3 files in a folder on the SD chip when using the /MP3 folder name. But there is no way to programatically ask how many files are in that folder. This is essential to prevent a program from trying to play track number 8,122, or 4,333 for example if only 3,000 MP3's are in that folder.

This command (or similar ones) for example will not work:

NrFolderFiles = myDFPlayer.readFileCountsInFolder("/MP3");
NrFolderFiles = myDFPlayer.readFileCountsInFolder("MP3");
NrFolderFiles = myDFPlayer.readFileCountsInFolder(/MP3);
NrFolderFiles = myDFPlayer.readFileCountsInFolder("SD:/MP3");

Is there a command that will work? If not, can an update be made to the library? Thanks!