the hasBeenRestarted allocation property checks against its task events, which can sometimes be null (#20383)

.changelog/20383.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+ui: Fix an issue where the job status box would error if an allocation had no task events
+```

ui/app/models/allocation.js

@@ -81,9 +81,9 @@ export default class Allocation extends Model {
 
   get hasBeenRestarted() {
     return this.states
-      .map((s) => s.events.content)
+      .map((s) => s.events?.content)
       .flat()
-      .find((e) => e.type === 'Restarting');
+      .find((e) => e?.type === 'Restarting');
   }
 
   @attr healthChecks;