PHP注意：尝试获取非对象行638的属性

Notice: Trying to get property of non-object in /var/www/admin/data/www/test.com/wp-content/themes/bd/inc/blt-functions.php on line 638

       if(!function_exists('blt_get_comment')){
            function blt_get_comment($comment, $args, $depth){

 (LINE 638)     $author_comment_id = get_user_by('email', get_comment_author_email())->ID; 
                $comment_score = get_comment_meta( get_comment_ID(), 'blt_score', true );
                if(empty($comment_score)){
                    $comment_score = 0;
                }

It means, get_user_by is returning FALSE, meaning user couldn't be found. You need to do a check, like so:

 $user = get_user_by('email', get_comment_author_email());
 $author_comment_id = (($user != FALSE) ? $user->ID : 0);
 //or a check like this
 if(!$user)
 {
     return false;
 }

Note, it might be a good idea to check later on, if $author_comment_id is not 0