$ perl -MData::Dump -e 'my $x = []; dd !!$x->[0]->{"aaa"}; dd $x;'
""
[{}]
$ perl -MList::Util=first -MData::Dump -e 'my @x; dd [first {$_} @x]'
[undef]
$ perl -le 'print( (undef)->{"aaa"} )'
Can't use an undefined value as a HASH reference at -e line 1.
$ perl -MList::Util=first -MData::Dump -e \
  'my @x; my $y=[first {$_} @x]; dd $y; dd !!$y->[0]->{"aaa"}; dd $y'
[undef]
""
[{}]