The error is thrown immediately after I do the following:

....

    #open the mail folder, in rw mode
    my $folder = Mail::Box::Maildir->new(
        folder            => $args{maildir},
        access            => 'rw',
        remove_when_empty => 0
      )
      or croak "Cannot open Maildir " . $args{maildir} . ": $!";

    #run thru all messages
    foreach my $id ( $folder->messageIds ) {


        my $message = $folder->messageId($id);
        next if $message->isDeleted;
....
[download]

The call to $folder->messageId($id) die's with the error.

Actually, earlier I had posted the same message on the Mail::Box's mailing list, hence the reference to the line number of the code base

I will take your advice and upgrade to the latest stable build. Thanks