i have the same problem !
but i have no Exception ! :(
server is TYPSoft FTP Server
0 files found with dirDetails(client.pwd());
but 0 with dir(client.pwd()); too !!
dir(); works perfectly but i can't make difference between files and directories !
220 TYPSoft FTP Server 1.10 ready...
---> USER Anonymous
331 Password required for Anonymous.
---> PASS ********
230 User Anonymous logged in.
---> PWD
257 "/" is current directory.
---> PASV
227 Entering Passive Mode (127,0,0,1,7,54).
---> LIST /
150 Opening data connection for directory list.
226 Transfer complete.
and -> client.dirDetails("/").length = 0