fix "Undefined array key" errors in various scripts (librenms#18412)

* fix Undefined array error

Fixes error: PHP message: PHP Error(2): Undefined array key "note" in /opt/librenms/includes/html/forms/alert-notes.inc.php:30

* Fix Undefined array key "device" in syslog.inc.php

Fixes "Undefined array key "device" in /opt/librenms/includes/html/pages/syslog.inc.php:21"

Author: CKeckNorthIO

includes/html/forms/alert-notes.inc.php

@@ -27,7 +27,7 @@
 
 $alert_id = $vars['alert_id'];
 $sub_type = $vars['sub_type'];
-$note = strip_tags($vars['note']) ?: '';
+$note = isset($vars['note']) ? strip_tags($vars['note']) : '';
 $status = 'error';
 
 if (is_numeric($alert_id)) {

includes/html/pages/syslog.inc.php

@@ -18,7 +18,7 @@
 
 $no_refresh = true;
 $param = [];
-$device_id = (int) $vars['device'];
+$device_id = isset($vars['device']) ? (int) $vars['device'] : null;
 
 if (isset($vars['action']) && $vars['action'] == 'expunge' && \Auth::user()->hasGlobalAdmin()) {
     \App\Models\Syslog::truncate();