Lang php Notice

PS vz.: 5.7.2
module Vz.: 0.9.13
lang module: polylang
PrestaShopIntegration::psLang() – php NOTICE
$lang is not defined, if defined( ‘ICL_LANGUAGE_CODE’ ) OR function_exists( ‘pll_current_language’ )
Need to be defined before.

function psLang() {
	if ( $this->id_lang )
		return $this->id_lang;

+       $lang = '';
	if ( defined( 'ICL_LANGUAGE_CODE' ) )
		$iso_code = ICL_LANGUAGE_CODE;
	elseif ( function_exists( 'pll_current_language' ) )
		$iso_code = pll_current_language();
	elseif ( $lang = get_bloginfo('language') )
		$iso_code = substr( $lang, 0, 2 );

	if ( $iso_code ) {
		if ($this->psdb) {
			$id_lang = $this->psdb->get_var( '
				SELECT <code>id_lang</code>
				FROM <code>'.$this->psprefix.'lang</code>
				WHERE <code>active</code> = 1 AND (<code>iso_code</code> = "'.$iso_code.'" OR <code>iso_code</code> = "'.$lang.'")' );
			if ( $id_lang > 0 )
				return ( $this->id_lang = $id_lang );
		}
	}

	return ( $this->id_lang = $this->psConfiguration( 'PS_LANG_DEFAULT' ) );
}