chore: update sanitizeFallbackLocale func

Author: jessrynkar

packages/payload/src/fields/hooks/afterRead/promise.ts

@@ -160,19 +160,9 @@ export const promise = async ({
     if (fallbackLocale && fallbackLocale !== locale) {
       let fallbackValue
       const isNullOrUndefined = typeof value === 'undefined' || value === null
-      const fallbackIsArray =
-        Array.isArray(fallbackLocale) ||
-        (fallbackLocale.startsWith('[') && fallbackLocale.endsWith(']'))
-
-      if (fallbackIsArray) {
-        const formattedFallback = Array.isArray(fallbackLocale)
-          ? fallbackLocale
-          : fallbackLocale
-              .slice(1, -1)
-              .split(',')
-              .map((l) => l.trim())
-
-        for (const locale of formattedFallback) {
+
+      if (Array.isArray(fallbackLocale)) {
+        for (const locale of fallbackLocale) {
           const val = siblingDoc[field.name!]?.[locale]
 
           if (val !== undefined && val !== null && val !== '') {

packages/payload/src/utilities/sanitizeFallbackLocale.ts

@@ -2,7 +2,7 @@ import type { SanitizedLocalizationConfig } from '../config/types.js'
 import type { TypedLocale } from '../index.js'
 
 interface Args {
-  fallbackLocale: false | TypedLocale
+  fallbackLocale: false | TypedLocale | TypedLocale[]
   locale: string
   localization: SanitizedLocalizationConfig
 }
@@ -26,7 +26,10 @@ export const sanitizeFallbackLocale = ({
     hasFallbackLocale = Boolean(localization && localization.fallback)
   }
 
-  if (fallbackLocale && !['false', 'none', 'null'].includes(fallbackLocale)) {
+  if (
+    fallbackLocale &&
+    !['false', 'none', 'null'].includes(!Array.isArray(fallbackLocale) ? fallbackLocale : '')
+  ) {
     hasFallbackLocale = true
   }
 
@@ -52,5 +55,16 @@ export const sanitizeFallbackLocale = ({
     fallbackLocale = null
   }
 
+  if (
+    typeof fallbackLocale === 'string' &&
+    fallbackLocale.startsWith('[') &&
+    fallbackLocale.endsWith(']')
+  ) {
+    fallbackLocale = fallbackLocale
+      .slice(1, -1)
+      .split(',')
+      .map((l) => l.trim())
+  }
+
   return fallbackLocale as null | string
 }