fix: use pReply->lastSendIndex instead while updating commitIndex

source/libs/sync/src/syncAppendEntries.c

@@ -207,12 +207,13 @@ int32_t syncNodeOnAppendEntries(SSyncNode* ths, const SRpcMsg* pRpcMsg) {
   accepted = true;
 
 _SEND_RESPONSE:
+  pEntry = NULL;
   pReply->matchIndex = syncLogBufferProceed(ths->pLogBuf, ths, &pReply->lastMatchTerm);
   bool matched = (pReply->matchIndex >= pReply->lastSendIndex);
   if (accepted && matched) {
     pReply->success = true;
     // update commit index only after matching
-    (void)syncNodeUpdateCommitIndex(ths, TMIN(pMsg->commitIndex, pEntry->index));
+    (void)syncNodeUpdateCommitIndex(ths, TMIN(pMsg->commitIndex, pReply->lastSendIndex));
   }
 
   // ack, i.e. send response