Thanks for the replies! The goal was to replace [...]->[0] with first to make the code a bit more readable but at this point I might as well leave it alone (performance isn't really a concern). Out of curiosity, why does this still work: 
no autovivification;

my @x = ({"aaa" => 100});
say Dumper([grep { $_->{"aaa"} < 4 } @x]->[0]->{"aaa"});

#$VAR1 = undef;

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In reply to Re: Why are these undefs different? by Anonymous Monk
in thread Why are these undefs different? by Anonymous Monk

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