fix(plugin-nested-docs): corrects data shape of breadcrumbs returned in hooks (#10866)

### What?
The `plugin-nested-docs` returns an array of breadcrumbs - the
`resaveChildren` file accidentally processed the breadcrumbs twice, once
where the data is updated and once within the `populateBreadcrumbs`
function which was causing the objects to be double nested.

### How?
Removes the extra nesting from `resaveChildren` file and allows the
`populateBreadcrumbs` to return the final data.

Fixes #10855

packages/plugin-nested-docs/src/hooks/resaveChildren.ts

@@ -81,10 +81,7 @@ const resave = async ({ collection, doc, draft, pluginConfig, req }: ResaveArgs)
           await req.payload.update({
             id: child.id,
             collection: collection.slug,
-            data: {
-              ...child,
-              [breadcrumbSlug]: await populateBreadcrumbs(req, pluginConfig, collection, child),
-            },
+            data: populateBreadcrumbs(req, pluginConfig, collection, child),
             depth: 0,
             draft: isDraft,
             locale: req.locale,

test/plugin-nested-docs/int.spec.ts

@@ -76,7 +76,6 @@ describe('@payloadcms/plugin-nested-docs', () => {
           },
         })
       }
-
       // update parent doc
       await payload.update({
         collection: 'pages',
@@ -110,6 +109,91 @@ describe('@payloadcms/plugin-nested-docs', () => {
       // @ts-ignore
       expect(lastUpdatedChildBreadcrumbs[0].url).toStrictEqual('/11-children-updated')
     })
+
+    it('should return breadcrumbs as an array of objects', async () => {
+      const parentDoc = await payload.create({
+        collection: 'pages',
+        data: {
+          title: 'parent doc',
+          slug: 'parent-doc',
+          _status: 'published',
+        },
+      })
+
+      const childDoc = await payload.create({
+        collection: 'pages',
+        data: {
+          title: 'child doc',
+          slug: 'child-doc',
+          parent: parentDoc.id,
+          _status: 'published',
+        },
+      })
+
+      // expect breadcrumbs to be an array
+      expect(childDoc.breadcrumbs).toBeInstanceOf(Array)
+      expect(childDoc.breadcrumbs).toBeDefined()
+
+      // expect each to be objects
+      childDoc.breadcrumbs?.map((breadcrumb) => {
+        expect(breadcrumb).toBeInstanceOf(Object)
+      })
+    })
+
+    it('should update child doc breadcrumb without affecting any other data', async () => {
+      const parentDoc = await payload.create({
+        collection: 'pages',
+        data: {
+          title: 'parent doc',
+          slug: 'parent',
+        },
+      })
+
+      const childDoc = await payload.create({
+        collection: 'pages',
+        data: {
+          title: 'child doc',
+          slug: 'child',
+          parent: parentDoc.id,
+          _status: 'published',
+        },
+      })
+
+      await payload.update({
+        collection: 'pages',
+        id: parentDoc.id,
+        data: {
+          title: 'parent updated',
+          slug: 'parent-updated',
+          _status: 'published',
+        },
+      })
+
+      const updatedChild = await payload
+        .find({
+          collection: 'pages',
+          where: {
+            id: {
+              equals: childDoc.id,
+            },
+          },
+        })
+        .then(({ docs }) => docs[0])
+
+      if (!updatedChild) {
+        return
+      }
+
+      // breadcrumbs should be updated
+      expect(updatedChild.breadcrumbs).toHaveLength(2)
+
+      expect(updatedChild.breadcrumbs?.[0]?.url).toStrictEqual('/parent-updated')
+      expect(updatedChild.breadcrumbs?.[1]?.url).toStrictEqual('/parent-updated/child')
+
+      // no other data should be affected
+      expect(updatedChild.title).toEqual('child doc')
+      expect(updatedChild.slug).toEqual('child')
+    })
   })
 
   describe('overrides', () => {