I don't know why you get that result. It doesn't happen when I try this bit that should be equivalent:

use strict;
use warnings;

my $dep_name = 'Salisbury';
my $dep_tip = bless( {
                 '_location' => $dep_name,
                 '_id' => 259,
                 '_key' => 'SLSBRY'
               }, 'Object::Location' );

if ( ! defined $dep_tip ){
  use Carp;
  croak ( "DATA ERROR: Could not find any location for '$dep_name'" );
}
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