bugfix(function not exists): add actions when add_action function exists

src/Reminder.php

@@ -7,9 +7,11 @@ class Reminder {
 	private $logo_url = 'logo-url';
 
 	public function __construct() {
+		if ( function_exists( 'add_action' ) ) {
 			add_action( 'admin_enqueue_scripts', array( $this, 'enqueue_reminder_script' ) );
 			add_action( 'admin_footer', array( $this, 'display_html_element' ) );
 		}
+	}
 
 	public function enqueue_reminder_script() {
 		if ( ! $this->is_plugin_activated() ) {