cherry pick #4219 to 1.3.4-pre (#4220)

dolphinscheduler-dao/src/main/java/org/apache/dolphinscheduler/dao/utils/DagHelper.java

@@ -374,11 +374,14 @@ public class DagHelper {
                                  DAG<String, TaskNode, TaskNodeRelation> dag,
                                  Map<String, TaskInstance> completeTaskList,
                                  Map<String, TaskNode> skipTaskNodeList){
+        if (!dag.containsNode(skipNodeName)) {
+            return;
+        }
         skipTaskNodeList.putIfAbsent(skipNodeName, dag.getNode(skipNodeName));
         Collection<String> postNodeList = dag.getSubsequentNodes(skipNodeName);
-        for(String post : postNodeList){
+        for (String post : postNodeList) {
             TaskNode postNode = dag.getNode(post);
-            if(isTaskNodeNeedSkip(postNode, skipTaskNodeList)){
+            if (isTaskNodeNeedSkip(postNode, skipTaskNodeList)) {
                 setTaskNodeSkip(post, dag, completeTaskList, skipTaskNodeList);
             }
         }