Trouble with marshalling parrot backtraces into Perl 6 objects

bt.pl

try {
    die 'foo';
}

# I'd expect a Parcel here,since .backtrace returns an RPA
my $p_bt =
    pir::perl6ize_type__PP(
        nqp::getattr(pir::perl6_decontainerize__PP($!), Exception, '$!ex').backtrace
    );

# dies with   Method 'gist' not found for invocant of class 'Hash'
# if run:
# say $p_bt;


# this one says 'Parcel':
pir::say pir::typeof__SP
        nqp::getattr(pir::perl6_decontainerize__PP($!), Exception, '$!ex').backtrace;