Better to test the match result. Consider:

#!/usr/bin/perl
use strict;
use warnings;

for my $str ('Matched', 'No match') {
    $str =~ /(\w*ed)/;
    print "defined: Matched $1 for '$str'\n" if defined $1;
}

for my $str ('Matched', 'No match') {
    print "match: Matched $1 for '$str'\n" if $str =~ /(\w*ed)/;
}
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Prints:

defined: Matched Matched for 'Matched'
defined: Matched Matched for 'No match'
match: Matched Matched for 'Matched'
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