我编写了一个插件来处理登录功能。该插件在内容过滤器中检查登录信息，并仅为登录用户显示。wp\\u signon显示错误/警告

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<?php
/**
 * Plugin Name: test-plugin
 * Description: my test plugin writing experience in WordPress
 * Version: 1.0
 * Author: KK
*/

function my_add_shortcodes() {
    add_shortcode( \'my-login-form\', \'my_login_form_shortcode\' );
}

function my_login_form_shortcode() {
    ob_start();
    require_once(\'forms/login.php\');
    return ob_get_clean();
}

function filter_content( $content ) {
        if ( ! empty( filter_input( INPUT_POST, \'login_submit\' ) ) ) {
            $login_info = array_map( \'sanitize_text_field\', $_POST );
            $email = $login_info[\'email\'];
            $password = $login_info[\'password\'];
            echo \'email \'.$email.\' password \'.$password;
            $user = wp_signon(array(\'user_login\' => $email, \'user_password\' => $password, \'remember\' => $rememberme), is_ssl());
            if( $user instanceof WP_User){
                echo " check_credentials ".$user->display_name;
                wp_set_current_user($user->ID, $user->user_login);
            } else {
                if( is_wp_error($user)){
                    echo $user->get_error_message();
                    $this->$error = "Email or Password error";
                    return $this->$error;
                } 
            }
        } else {
            return "<p>[my-login-form]</p";
        }
        
        return $content;
}
    
add_action( \'init\', \'my_add_shortcodes\' );
add_filter( \'the_content\', \'filter_content\' );