if ($rating_count >= 1) {
    $main_entity["aggregateRating"] = [
        "@type" => "AggregateRating", 
        "ratingValue" => (float) number_format($rating, 1, '.', ''), 
        "bestRating" => "5", 
        "worstRating" => "1", 
        "ratingCount" => (int) $rating_count, 
        "reviewCount" => (int) $rating_count
    ];
}