Move typecheck thrower to separate method
Move typecheck thrower to separate method

so we can use it from multiple places

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