How to check if a dir is empty in NSIS

I've just found a rogue directory being left behind by one of my dev tests, so in the next release I'd like to handle it automatically where it already exists on a users PC (plus it is about time I got my head around some NSIS).

The folder in question is %LOCALAPPDATA%\cache\picard, so I need to delete the picard folder if it exists (this I can do), then delete the cache dir if it is now empty (this I am stuck on).

The code so far:

!macro CustomCodePreInstall
   ${If} ${FileExists} "$LOCALAPPDATA\cache\picard\*.*"
     RMDir /r "$LOCALAPPDATA\cache\picard"
     ${If} ${FileExists} "$LOCALAPPDATA\cache\*.*"
       MessageBox MB_OK "'$LOCALAPPDATA\cache\*.*' exists"
       ${If} ${FileExists} "$LOCALAPPDATA\cache"
         MessageBox MB_OK "'$LOCALAPPDATA\cache' exists"
       ${EndIf}
     ${EndIf}
   ${EndIf}
!macroend


Running this the picard folder is deleted, but the checks for the cache folder (with and without *.*) both prove truthy, despite that the folder is definitely now empty.

So is there a predefined way to check if a directory is empty, or otherwise how could I include a function such as DirState in my code?