Use main query object property directly on libs/class.Apply.php

Hi All the authors of the plugin!

Please replace is_tag() conditional tag to a direct query object property $query->is_tag on class’s Apply method queryTag.

is_tag() is not intended to be used on pre_get_posts filter as it relies on global WP_Query object which is not ready/created at that point. (1)
This produces “PHP Notice: is_tag was called incorrectly.” (WP core @v5.3.2) (2)

(1) https://developer.www.ads-software.com/reference/hooks/pre_get_posts/#a-warning-about-conditional-functions
(2) https://core.trac.www.ads-software.com/browser/tags/5.3.2/src/wp-includes/query.php#L287

Method in question (download-manager @v3.0.9)

function queryTag($query)
    {
        if (is_tag() && $query->is_main_query()) {
            $post_type = get_query_var('post_type');
            if (!is_array($post_type))
                $post_type = array('post', 'wpdmpro');
            else
                $post_type = array_merge($post_type, array('post', 'wpdmpro'));
            $query->set('post_type', $post_type);
        }
        return $query;
    }

Thanks

Martins