fix(gatsby-source-wordpress): fix preview issues (#37492)

* add fallback array to prevent errors when cachedNodeIds aren't passed

* if there's a token we're previewing - also await non node root fields for previews

packages/gatsby-source-wordpress/src/steps/source-nodes/index.ts

@@ -12,24 +12,19 @@ import { sourcePreviews } from "~/steps/preview"
 const sourceNodes: Step = async helpers => {
   const { cache, webhookBody, refetchAll } = helpers
 
+  // fetch non-node root fields such as settings.
+  // For now, we're refetching them on every build
+  const nonNodeRootFieldsPromise = fetchAndCreateNonNodeRootFields()
+
   // if this is a preview we want to process it and return early
-  if (webhookBody.preview) {
+  if (webhookBody.token && webhookBody.userDatabaseId) {
     await sourcePreviews(helpers)
-
+    await nonNodeRootFieldsPromise
     return
   }
-  // if it's not a preview but we have a token
-  // we should source any pending previews then continue sourcing
-  else if (webhookBody.token && webhookBody.userDatabaseId) {
-    await sourcePreviews(helpers)
-  }
 
   const now = Date.now()
 
-  // fetch non-node root fields such as settings.
-  // For now, we're refetching them on every build
-  const nonNodeRootFieldsPromise = fetchAndCreateNonNodeRootFields()
-
   const lastCompletedSourceTime =
     webhookBody.refreshing && webhookBody.since
       ? webhookBody.since

packages/gatsby-source-wordpress/src/steps/source-nodes/update-nodes/wp-actions/update.js

@@ -24,7 +24,7 @@ export const fetchAndCreateSingleNode = async ({
   singleName,
   id,
   actionType,
-  cachedNodeIds,
+  cachedNodeIds = [],
   token = null,
   isPreview = false,
   isDraft = false,