You are responsible for propagating $@ to the outer most eval.

eval {
   die "borg";
};
warn "whoops $@" if $@;

eval {
    eval {
        die "borg";
    };
    die $@ if $@; # essentially "rethrow" an "exception" if it occured
};

warn "whoops $@" if $@;
__END__
whoops borg at - line 2.
whoops borg at - line 8.
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