Hello Monks, I got stuck with a "Can't use an undefined value as an ARRAY reference at ..." error when trying to push a struct using MooX::Struct onto an array. Please apologize I am still a novice monk and I don't understand why this error happens. I probably did some smaller or larger mistake, but have no clue what could be wrong. :(

Here a stripped-down piece of code. It fails at the line with the push.

use strict;
use warnings;
use diagnostics;
use 5.014;  # so push/pop/etc work on scalars (experimental)

use MooX::Struct -rw, Dirnode => [ qw( $dirname @subdlist ) ];
my $dirroot = crawldir( ".");

sub crawldir {
    my $curpath = shift;
    my $dno = Dirnode[];
    $dno->dirname( $curpath );

    opendir(DIR, $curpath);
    my @files = readdir(DIR);
    closedir(DIR);
    print "crawldir in directory ", $dno->dirname, "\n";
    foreach (@files) {
        next if $_ eq '.' or $_ eq '..';
        my $file_path = "$curpath/$_";
        $file_path =~ s|/+|/|g;
        if (-d $file_path) {
           print "crawldir in directory ", $dno->dirname, ": calling c
+rawldir( $curpath\/$_)\n";
           push @{$dno->subdlist}, crawldir( "$curpath\/$_" );
        }
    }
    return $dno;
}
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