Prevent error when accessing optional needs in pipeline graph

It is possible when building the links arrays for needs
that a defined jobs in the needs array does not exist in
the object that contains all jobs. This is because a job
with rules may or may not exist at execution time.
This commit access safely the needs or return an empty value.

Changelog: fixed

app/assets/javascripts/pipelines/components/parsing_utils.js

@@ -80,7 +80,7 @@ export const makeLinksFromNodes = (nodes, nodeDict) => {
 export const getAllAncestors = (nodes, nodeDict) => {
   const needs = nodes
     .map((node) => {
-      return nodeDict[node].needs || '';
+      return nodeDict[node]?.needs || '';
     })
     .flat()
     .filter(Boolean);