Add missing private error handling method
Add missing private error handling method

Spotted by jjatria++ .  Also restructure a bit to prevent repetition

labster/rakudo,tbrowder/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,rakudo/rakudo,tbrowder/rakudo,rakudo/rakudo,salortiz/rakudo,salortiz/rakudo,salortiz/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,rakudo/rakudo,rakudo/rakudo,labster/rakudo,tbrowder/rakudo,labster/rakudo,salortiz/rakudo,labster/rakudo,tbrowder/rakudo,rakudo/rakudo,MasterDuke17/rakudo,labster/rakudo,MasterDuke17/rakudo,rakudo/rakudo,MasterDuke17/rakudo,labster/rakudo,salortiz/rakudo,tbrowder/rakudo,salortiz/rakudo