enhance: Add log for case which target not update as expected

Signed-off-by: Wei Liu <[email protected]>

internal/querycoordv2/observers/target_observer.go

@@ -383,7 +383,16 @@ func (ob *TargetObserver) shouldUpdateCurrentTarget(ctx context.Context, collect
 	collectionReadyLeaders := make([]*meta.LeaderView, 0)
 	for channel := range channelNames {
 		channelReadyLeaders := lo.Filter(ob.distMgr.LeaderViewManager.GetByFilter(meta.WithChannelName2LeaderView(channel)), func(leader *meta.LeaderView, _ int) bool {
-			return utils.CheckDelegatorDataReady(ob.nodeMgr, ob.targetMgr, leader, meta.NextTarget) == nil
+			err := utils.CheckDelegatorDataReady(ob.nodeMgr, ob.targetMgr, leader, meta.NextTarget)
+			if err != nil {
+				log.Info("leader is not available",
+					zap.Int64("collectionID", collectionID),
+					zap.Int64("nodeID", leader.ID),
+					zap.String("channelName", channel),
+					zap.Error(err))
+				return false
+			}
+			return true
 		})
 
 		// to avoid stuck here in dynamic increase replica case, we just check available delegator number