fix: add nil check when accessing workflow nodes in retry logic

When retrying a workflow with parameter override, the code accesses
wf.Status.Nodes[nodeID] without checking if the nodeID exists. Since
Nodes is a map[string]NodeStatus, accessing a non-existent key returns
a zero value without panicking, but it's safer to explicitly check
existence using the comma-ok idiom.

This prevents potential issues where toReset might contain nodeIDs that
don't exist in wf.Status.Nodes in edge cases.

Also renamed the second 'ok' variable to 'okNode' to avoid shadowing
the first 'ok' variable.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
Signed-off-by: Yu-Hong Shen <stanley.shen2003@gmail.com>

Author: stanleyshen2003

workflow/util/util.go

@@ -1240,9 +1240,12 @@ func FormulateRetryWorkflow(ctx context.Context, wf *wfv1.Workflow, restartSucce
 			if toDelete[nodeID] {
 				continue
 			}
-			n := wf.Status.Nodes[nodeID]
+			n, ok := wf.Status.Nodes[nodeID]
+			if !ok {
+				continue
+			}
 			if n.Type == wfv1.NodeTypeTaskGroup || n.Type == wfv1.NodeTypeStepGroup {
-				if dagNode, ok := nodesMap[nodeID]; ok {
+				if dagNode, okNode := nodesMap[nodeID]; okNode {
 					for childID := range getChildren(dagNode) {
 						toDelete[childID] = true
 					}