If an element is empty, it has no text() child nodes, so you can't call any methods on any of them. But even if it had, you don't want to remove the child nodes of the text(), but the child nodes of their parent, i.e. the otherTitle.

Note how the following script is SSCCE (which your question wasn't, which made it harder for us to help you):

#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

use XML::LibXML;

for my $other_title (
    '<alt-title origin="tilte"><otherTitle/></alt-title>',
    '<alt-title origin="tilte"><otherTitle>old value</otherTitle></alt
+-title>',
) {
    my $xml = qq(
    <file>
      <body>
        <group>
          <unit id="3Ojs1SLwMmEHK8mJ0_dc2:43">
            $other_title
          </unit>
        </group>
      </body>
    </file>
    );

    my $dom  = 'XML::LibXML'->load_xml(string => $xml);

    my ($other_title) = $dom->findnodes('//file/body/group/unit/alt-ti
+tle/otherTitle');
    if ($other_title->findnodes('text()')) {
        $other_title->removeChildNodes;
    }
    $other_title->appendText('new value');
    print $dom;
}

[download]
($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

[download]

In reply to Re: Update nodes in XML document by choroba
in thread Update nodes in XML document by corfuitl

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