Fix null createdAt crash in Feedback vote results after Gen2 trigger migration

The Gen1->Gen2 Firestore trigger migration (#1664) made the vote
aggregation fire before serverTimestamp() resolves, writing null
createdAt/updatedAt into aggregated sessionVotes docs. The Feedback app
then crashed on `value2.createdAt.toDate()` with
"TypeError: can't access property toDate, h.createdAt is null".

- aggregateVotes.ts: normalizeVoteTimestamps() falls back to the
  snapshot's server-assigned createTime/updateTime when the field is
  null, so new aggregated docs never store a null timestamp.
- getVoteResultSelectorSelector.js: guard the .toDate() calls and skip
  entries with no usable date, so already-corrupted prod docs no longer
  crash the whole results view.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: HugoGresse

functions/src/triggers/aggregateVotes.ts

@@ -14,7 +14,7 @@ export const aggregateVotesCreate = onDocumentCreated(
         }
         return incrementVoteAggregate(
             admin.firestore(),
-            new Vote(snapshot.id, snapshot.data() as VoteData)
+            new Vote(snapshot.id, normalizeVoteTimestamps(snapshot))
         )
     }
 )
@@ -28,11 +28,27 @@ export const aggregateVotesUpdate = onDocumentUpdated(
         }
         return incrementVoteAggregate(
             admin.firestore(),
-            new Vote(change.after.id, change.after.data() as VoteData)
+            new Vote(change.after.id, normalizeVoteTimestamps(change.after))
         )
     }
 )
 
+// Gen2 (Eventarc) triggers can fire before a serverTimestamp() sentinel
+// resolves, leaving createdAt/updatedAt null in the snapshot. The Gen1 API
+// hid that intermediate write. Fall back to the snapshot's server-assigned
+// createTime/updateTime so the aggregated sessionVotes doc never stores a
+// null timestamp (which crashes the Feedback app's .toDate() calls).
+const normalizeVoteTimestamps = (
+    snapshot: FirebaseFirestore.DocumentSnapshot
+): VoteData => {
+    const data = snapshot.data() as VoteData
+    return {
+        ...data,
+        createdAt: data.createdAt ?? snapshot.createTime ?? snapshot.updateTime,
+        updatedAt: data.updatedAt ?? snapshot.updateTime ?? snapshot.createTime,
+    }
+}
+
 export const incrementVoteAggregate = (
     firestoreDb: FirebaseFirestore.Firestore,
     vote: Vote

src/feedback/talk/core/getVoteResultSelectorSelector.js

@@ -62,10 +62,23 @@ export const getVoteResultSelectorSelector = createSelector(
                         // Empty object due to deletion
                         return
                     }
+                    // A regression (Gen2 trigger migration) wrote some
+                    // aggregated votes with null createdAt/updatedAt. Guard
+                    // the .toDate() calls so one bad entry can't crash the
+                    // whole results view; fall back to whichever date exists.
+                    const updatedAt =
+                        value2.updatedAt?.toDate?.() ??
+                        value2.createdAt?.toDate?.() ??
+                        null
+                    const createdAt = value2.createdAt?.toDate?.() ?? updatedAt
+                    if (!updatedAt) {
+                        // No usable timestamp, skip this corrupted entry
+                        return
+                    }
                     transformResult[key].push({
                         ...value2,
-                        updatedAt: value2.updatedAt.toDate(),
-                        createdAt: value2.createdAt.toDate(),
+                        updatedAt,
+                        createdAt,
                     })
                 })
                 transformResult[key] = transformResult[key].sort(