Correctly preventing spamming of the subscribe button

in current implementation, every time the user clicks subscribe, a new listener gets added on top of the existing ones, causing multiple handlers to execute and an infinite loop of event listener additions.

Author: iMattPro

styles/all/template/webpush.js

@@ -237,7 +237,7 @@ function PhpbbWebpush() {
 	async function subscribeButtonHandler(event) {
 		event.preventDefault();
 
-		subscribeButton.addEventListener('click', subscribeButtonHandler);
+		subscribeButton.removeEventListener('click', subscribeButtonHandler);
 
 		try {
 			// Prevent the user from clicking the subscribe button multiple times.
@@ -288,6 +288,8 @@ function PhpbbWebpush() {
 			}
 			console.error('Push subscription error:', error);
 			phpbb.alert(subscribeButton.getAttribute('data-l-err'), error.message || subscribeButton.getAttribute('data-disabled-msg'));
+		} finally {
+			subscribeButton.addEventListener('click', subscribeButtonHandler);
 		}
 	}