I think this is a bug in 1.6.2. ListDirectoryInGuest fails differently in VMWare Workstation and VI (ESX) for listing empty directories.
Workstation: GetNumProperties returns VIX_E_UNRECOGNIZED_PROPERTY when trying to get the number of results.
VI (ESX): returns 2, probably E_FILE_NOT_FOUND, although in VMWARE errors this is out of memory on job wait.
I think both are wrong and should fail the job with a specific error code that there're no files or subdirectories in this directory.