set default for "Newer than" option

dist/panel-triggers/partials/options_tab.html

@@ -110,8 +110,8 @@
       <label class="gf-form-label width-10">Newer than</label>
       <input class="gf-form-input width-8"
         ng-model="ctrl.panel.highlightNewerThan"
-        ng-model-onblur
+        placeholder="1h"
-        ng-change="ctrl.render()">
+        ng-model-onblur ng-change="ctrl.render()">
     </div>
     <gf-form-switch class="gf-form"
       label-class="width-16"

dist/panel-triggers/triggers_panel_ctrl.js

@@ -602,9 +602,14 @@ System.register(['lodash', 'jquery', 'moment', '../datasource-zabbix/utils', 'ap
         }, {
           key: 'isNewTrigger',
           value: function isNewTrigger(trigger) {
-            var highlightIntervalMs = utils.parseInterval(this.panel.highlightNewerThan);
+            try {
+              var highlightNewerThanDefault = '1h';
+              var highlightIntervalMs = utils.parseInterval(this.panel.highlightNewerThan || highlightNewerThanDefault);
               var durationSec = Date.now() - trigger.lastchangeUnix * 1000;
               return durationSec < highlightIntervalMs;
+            } catch (e) {
+              return false;
+            }
           }
         }, {
           key: 'link',

src/panel-triggers/partials/options_tab.html

@@ -110,8 +110,8 @@
       <label class="gf-form-label width-10">Newer than</label>
       <input class="gf-form-input width-8"
         ng-model="ctrl.panel.highlightNewerThan"
-        ng-model-onblur
+        placeholder="1h"
-        ng-change="ctrl.render()">
+        ng-model-onblur ng-change="ctrl.render()">
     </div>
     <gf-form-switch class="gf-form"
       label-class="width-16"

src/panel-triggers/triggers_panel_ctrl.js

@@ -458,9 +458,14 @@ export class TriggerPanelCtrl extends PanelCtrl {
   }
 
   isNewTrigger(trigger) {
-    const highlightIntervalMs = utils.parseInterval(this.panel.highlightNewerThan);
+    try {
+      const highlightNewerThanDefault = '1h';
+      const highlightIntervalMs = utils.parseInterval(this.panel.highlightNewerThan || highlightNewerThanDefault);
       const durationSec = (Date.now() - trigger.lastchangeUnix * 1000);
       return durationSec < highlightIntervalMs;
+    } catch (e) {
+      return false;
+    }
   }
 
   link(scope, elem, attrs, ctrl) {