Fix problems panel broken when selecting triggers (#1960)

This PR fixes an issue where the problems panel breaks when you change
to query type to `Triggers`.

![](https://grafana.zendesk.com/attachments/token/MNBgVTPRKZkwa6TsMBbtBQdIp/?name=image.png)

How to reproduce:

1. Go to `Zabbix data source features` dashboard
2. Open Problems panel
3. Change`Query type` to `Triggers`
4. Select `Problems` from `Count by`
5. Change the `Group` to `Backend`
6. The problems panel should not error

---------

Co-authored-by: Zoltán Bedi <zoltan.bedi@gmail.com>

.changeset/purple-carrots-rhyme.md

@@ -0,0 +1,5 @@
+---
+'grafana-zabbix': patch
+---
+
+Fix problems panel broken when selecting triggers

src/panel-triggers/ProblemsPanel.tsx

@@ -63,7 +63,7 @@ export const ProblemsPanel = (props: ProblemsPanelProps): JSX.Element => {
     // Filter triggers by severity
     problemsList = problemsList.filter((problem) => {
       const severity = problem.severity !== undefined ? Number(problem.severity) : Number(problem.priority);
-      return triggerSeverity[severity].show;
+      return triggerSeverity[severity]?.show;
     });
 
     return problemsList;
@@ -100,8 +100,9 @@ export const ProblemsPanel = (props: ProblemsPanelProps): JSX.Element => {
     if (trigger.comments && options.allowDangerousHTML) {
       trigger.comments = trigger.comments.replace('\n', '<br>');
     }
-
-    trigger.lastchangeUnix = Number(trigger.lastchange);
+    if (trigger && typeof trigger === 'object') {
+      trigger.lastchangeUnix = Number(trigger.lastchange);
+    }
     return trigger;
   };