Obligatory "use XML::Twig" post from me.

For a quick and dirty fix for your problem, you could try

if (ref($var) eq 'ARRAY') { 
  ...
} elsif (ref($var) eq 'HASH') {
  ...
} else { 
  ...
  die "Var is of " . ref($var) . " type and will not be processed";
}
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