Writing a correct query?

I can’t seem to figure out how to construct the correct query

I made a custom taxonomy named “spotlight” which then has five or so terms. I want to act upon the taxonomy when someone views one of the spotlight archives. I only care about its value being “true” not which spotlight is viewed. This works if viewing a spotlight, but throws an error if viewing any non-spotlight archive (Warning: Undefined array key “spotlight”). Right now I have it beneath other taxonomies so that other taxonomies exit before reaching it, but that is bad practice. How do I perform a correct query?

add_action('pre_get_posts','tweak_archive_post_order')
function tweak_archive_post_order($query)
{if ($query->is_main_query() && is_archive() && $query->query_vars['category_name'] == 'skirted')
	{$query->set( 'posts_per_archive_page','-1');
	 $query->set( 'orderby','manual_sort_order');
	 $query->set( 'meta_key','manual_sort_order');
	 $query->set( 'order','ASC');
	}

[....]

elseif ($query->is_main_query() && is_archive() && ($query->query_vars['spotlight']))
	{$query->set('posts_per_archive_page','-1');
         $query->set('orderby','date');
         $query->set('order','ASC');
	}
}

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