fix(sync): compatibility for both mnode(use snapshot) and vnode(no snapshot)

source/libs/sync/src/syncMain.c

@@ -1215,13 +1215,14 @@ void syncNodeBecomeLeader(SSyncNode* pSyncNode) {
 
   // update sender private term
   SSyncSnapshotSender* pMySender = syncNodeGetSnapshotSender(pSyncNode, &(pSyncNode->myRaftId));
-  ASSERT(pMySender != NULL);
+  if (pMySender != NULL) {
     for (int i = 0; i < pSyncNode->pMatchIndex->replicaNum; ++i) {
       if ((pSyncNode->senders)[i]->privateTerm > pMySender->privateTerm) {
         pMySender->privateTerm = (pSyncNode->senders)[i]->privateTerm;
       }
     }
     (pMySender->privateTerm) += 100;
+  }
 
   // stop elect timer
   syncNodeStopElectTimer(pSyncNode);