enter code here

    $logged_in_user = wp_get_current_user();
    wp_get_current_user(); is return below object with empty values
     WP_User object {
        back_compat_keys => array(6) (
                   [user_firstname] => (string) first_name
                   [user_lastname] => (string) last_name
                   [user_description] => (string) description
                   [user_level] => (string) wp_user_level
                   [wp_usersettings] => (string) wp_user-settings
                   [wp_usersettingstime] => (string) wp_user-settings-time
                 )
        data => stdClass object
        ID => (int) 0
        caps => array(0)
        cap_key => null
        roles => array(0)
        allcaps => array(0)
        filter => null
     };

    //email is
    if($logged_in_user->ID != 0){
        $email = $logged_in_user->user_email;
    }