Point out which stage in a feed has a problem
Point out which stage in a feed has a problem

To do this, convert to `.ast`ing each stage as it's handled, instead of
before. This means we can then `.panic` on the stage with a problem, not
the entire feed.

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