fix(sync): fix hb-timer heap-use-after-free

source/libs/sync/src/syncMain.c

@@ -2059,6 +2059,7 @@ int32_t syncNodeOnHeartbeat(SSyncNode* ths, const SRpcMsg* pRpcMsg) {
       SyncLocalCmd* pSyncMsg = rpcMsgLocalCmd.pCont;
       pSyncMsg->cmd = SYNC_LOCAL_CMD_FOLLOWER_CMT;
       pSyncMsg->fcIndex = pMsg->commitIndex;
+      SyncIndex fcIndex = pSyncMsg->fcIndex;
 
       if (ths->syncEqMsg != NULL && ths->msgcb != NULL) {
         int32_t code = ths->syncEqMsg(ths->msgcb, &rpcMsgLocalCmd);
@@ -2066,7 +2067,7 @@ int32_t syncNodeOnHeartbeat(SSyncNode* ths, const SRpcMsg* pRpcMsg) {
           sError("vgId:%d, sync enqueue fc-commit msg error, code:%d", ths->vgId, code);
           rpcFreeCont(rpcMsgLocalCmd.pCont);
         } else {
-          sTrace("vgId:%d, sync enqueue fc-commit msg, fc-index:%" PRId64, ths->vgId, pSyncMsg->fcIndex);
+          sTrace("vgId:%d, sync enqueue fc-commit msg, fc-index:%" PRId64, ths->vgId, fcIndex);
         }
       }
     }