fix: ensure leavesFirst option works correctly in traverseFields utility (#11219)

We have to ensure the arguments are handled wherever we push to the callback stack, not when we execute the callback stack.

test/helpers/autoDedupeBlocksPlugin/index.ts

@@ -1,3 +1,4 @@
+import { dequal } from 'dequal/lite'
 import { type Block, type BlockSlug, type Config, traverseFields } from 'payload'
 
 export const autoDedupeBlocksPlugin =
@@ -68,7 +69,9 @@ export const deduplicateBlock = ({
         // Check if the fields are the same
         const jsonExistingBlock = JSON.stringify(existingBlock, null, 2)
         const jsonBlockToDeduplicate = JSON.stringify(dedupedBlock, null, 2)
-        if (jsonExistingBlock !== jsonBlockToDeduplicate) {
+        // dequal check of blocks with functions removed (through JSON.stringify+JSON.parse). We cannot check the strings,
+        // as the order of keys in the object is not guaranteed, yet it doesn't matter for the block fields.
+        if (!dequal(JSON.parse(jsonExistingBlock), JSON.parse(jsonBlockToDeduplicate))) {
           console.error('Block with the same slug but different fields found', {
             slug: dedupedBlock.slug,
             existingBlock: jsonExistingBlock,

test/package.json

@@ -86,5 +86,8 @@
     "ts-essentials": "10.0.3",
     "typescript": "5.7.3",
     "uuid": "10.0.0"
+  },
+  "dependencies": {
+    "dequal": "2.0.3"
   }
 }