Make R:I.SHORT-STRING handle null str correctly
Make R:I.SHORT-STRING handle null str correctly

Instead of blowing up with some LTA error about uncaught exceptions.

labster/rakudo,salortiz/rakudo,tony-o/rakudo,tony-o/rakudo,tbrowder/rakudo,tony-o/rakudo,salortiz/rakudo,tbrowder/rakudo,tony-o/rakudo,labster/rakudo,rakudo/rakudo,rakudo/rakudo,labster/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,tbrowder/rakudo,salortiz/rakudo,labster/rakudo,rakudo/rakudo,salortiz/rakudo,tbrowder/rakudo,tbrowder/rakudo,labster/rakudo,MasterDuke17/rakudo,tbrowder/rakudo,tony-o/rakudo,salortiz/rakudo,tony-o/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,rakudo/rakudo,labster/rakudo,MasterDuke17/rakudo,rakudo/rakudo,salortiz/rakudo,rakudo/rakudo