Exception #0 (Exception): Warning: explode() expects parameter 2 to be string, array given in /home/user/public_html/app/code/Mageplaza/LayeredNavigation/Plugin/Model/Adapter/Preprocessor.php on line 92
the code
if (($filter->getField() === 'category_ids')) {
$filterValue = implode(',', array_map([$this, 'validateCatIds'], explode(',', $filter->getValue())));