If you leave either the Printer Name or Paper Bin field empty (ie only putting something in one of those fields and leaving the other empty) then you will get a software error upon clicking Save Can't call method "save" without a package or object reference at /home/vagrant/kohaclone/patroncards/edit-profile.pl line 72.
Granted the error trapping here and feedback to the user leaves much to be desired, however, the behavior is as expected. Looking here: http://tinyurl.com/z3t845z will show that what we do is run a parameter check when asked to create a new Profile object. If all required parameters are not passed in, rather than returning a new object, -1 is returned which causes the attempt to invoke the save method to fail. Its old code, and I never go back to adding proper error trapping. It really should not return -1 in any case. In light of that, this bug should probably be closed RESOLVED WORKSFORME and another opened which addresses error trapping in the labels/patroncards code in general.