$self->log(LOGDEBUG, 'EDIT_USER: '. Dumper(
    { 
        state       => 'db_user',
        usr_id      => $self->client->param( 'usr_id' ),
        edit_usr_id => scalar( $self->client->param( 'edit_usr_id' ) ),
        mode        => $self->client->param( 'mode' )
    }
  )
);

##</code><code>##

sub param {
 ...
    return unless exists ...
    return ...;
}

##</code><code>##

Perl> sub x{ return };;

Perl> @b = ( 1,2,'a', x(), 5, 6 );;
Perl> print "@b";;
1 2 a 5 6

Perl> @b = ( 1,2,'a', scalar(  x() ), 5, 6 );;
Perl> print "@b";;
Use of uninitialized value in join or string at (eval 13) line 1
1 2 a  5 6