it shows in my reservation calendar this -Notice: Trying to get property of non-object

Question

Here is my code. Thankyou. It display like this Notice: Trying to get property of non-object.

 if($result->num_rows > 0){
            $eventListHTML = '<h2>Events on '.date("l, d M Y",strtotime($date)).'</h2>';
            $eventListHTML .= '<ul>';
            while($row = $result->fetch_assoc()){ 
                $eventListHTML .= '<li>'.$row['email'].'</li>';
            }
            $eventListHTML .= '</ul>';
        }
        echo $eventListHTML;
    }