default to default notification value on guild join

src/webpage/localuser.ts

@@ -742,6 +742,7 @@ class Localuser {
 							divy,
 							document.getElementById("bottomseparator"),
 						);
+						guildy.message_notifications = guildy.properties.default_message_notifications;
 					})();
 					break;
 				case "MESSAGE_REACTION_ADD":