github: support schedule events (#5810)

github/index.ts

@@ -574,10 +574,13 @@ async function subscribeSessionEvents() {
 }
 
 async function summarize(response: string) {
-  const payload = useContext().payload as IssueCommentEvent
   try {
     return await chat(`Summarize the following in less than 40 characters:\n\n${response}`)
   } catch (e) {
+    if (isScheduleEvent()) {
+      return "Scheduled task changes"
+    }
+    const payload = useContext().payload as IssueCommentEvent
     return `Fix issue: ${payload.issue.title}`
   }
 }