Fix infinihang on incorrect .split offset
Fix infinihang on incorrect .split offset

Further fix for RT#129773: https://rt.perl.org/Ticket/Display.html?id=129773

This is really gross, but all alternatives I could think of take at least 1.5x
more time to run. The `where` clause makes things ~14x slower. The nqp::istype
checks, make things ~1.5x slower. The .^lookup+cando candidate signature check
is about 10x slower.

MasterDuke17/rakudo,salortiz/rakudo,jonathanstowe/rakudo,MasterDuke17/rakudo,labster/rakudo,awwaiid/rakudo,samcv/rakudo,rakudo/rakudo,rakudo/rakudo,labster/rakudo,rakudo/rakudo,nbrown/rakudo,jonathanstowe/rakudo,awwaiid/rakudo,tbrowder/rakudo,Gnouc/rakudo,salortiz/rakudo,raydiak/rakudo,softmoth/rakudo,awwaiid/rakudo,raydiak/rakudo,tony-o/rakudo,nbrown/rakudo,sjn/rakudo,jonathanstowe/rakudo,nbrown/rakudo,usev6/rakudo,awwaiid/rakudo,salortiz/rakudo,Gnouc/rakudo,softmoth/rakudo,jonathanstowe/rakudo,MasterDuke17/rakudo,usev6/rakudo,tony-o/rakudo,lucasbuchala/rakudo,nbrown/rakudo,awwaiid/rakudo,softmoth/rakudo,softmoth/rakudo,labster/rakudo,sjn/rakudo,Gnouc/rakudo,Gnouc/rakudo,samcv/rakudo,labster/rakudo,salortiz/rakudo,MasterDuke17/rakudo,softmoth/rakudo,rakudo/rakudo,usev6/rakudo,sjn/rakudo,salortiz/rakudo,rakudo/rakudo,Gnouc/rakudo,jonathanstowe/rakudo,tony-o/rakudo,Gnouc/rakudo,lucasbuchala/rakudo,tony-o/rakudo,usev6/rakudo,sjn/rakudo,tbrowder/rakudo,labster/rakudo,samcv/rakudo,nbrown/rakudo,raydiak/rakudo,raydiak/rakudo,lucasbuchala/rakudo,sjn/rakudo,lucasbuchala/rakudo,nbrown/rakudo,usev6/rakudo,rakudo/rakudo,salortiz/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,samcv/rakudo,samcv/rakudo,lucasbuchala/rakudo,tbrowder/rakudo,labster/rakudo,tbrowder/rakudo,tony-o/rakudo,tbrowder/rakudo,tbrowder/rakudo,tony-o/rakudo