Sorry to bump an old thread, but I'm getting the same "local variable 'ret' referenced before assignment" error as the OP.
My laser is working, but I'm a complete noob here. This error is what I'd expect from a logical error in the code, but I don't quite follow the above discussion.
I'm running the 0.9.4 server as it seems to be the newest available.
I'd appreciate any help you can give.