The typed exception has changed and AFAIU the current behaviour is correct (cmp. also ticket 111924) :
$ perl6 -e 'my @a = [1], [2], [3]; say (map { @a[1 - $_][0] }, 0 .. 3).perl'
(2, 1, Failure.new(exception => X::Subscript::Negative.new(index => -1, type =>
Array)), Failure.new(exception => X::Subscript::Negative.new(index => -2, type
=> Array))).list
I added a test to S02-types/nested_arrays.t with commit
https://github.com/perl6/roast/commit/1ecd460c8e. I'm closing this ticket now.
