Net::SFTP's manual states this:

$local is optional. If not provided, the contents of the remote file $remote will be either discarded, if get is called in void context, or returned from get if called in a non-void context. Presumably, in the former case, you will use the callback function \&callback to "do something" with the contents of $remote.

you need to specify a local filename to save remote file to. (and make sure destination dirs exist before saving)

bw, bliako