fix: show the error message if images.loaderFile doesn't export a default function

packages/next/src/build/webpack/plugins/define-env-plugin.ts

@@ -110,7 +110,6 @@ function getImageConfig(
       imageSizes: config.images.imageSizes,
       path: config.images.path,
       loader: config.images.loader,
-      loaderFile: config.images.loaderFile,
       dangerouslyAllowSVG: config.images.dangerouslyAllowSVG,
       unoptimized: config?.images?.unoptimized,
       ...(dev

packages/next/src/shared/lib/get-img-props.ts

@@ -283,7 +283,7 @@ export function getImgProps(
     config = { ...c, allSizes, deviceSizes }
   }
 
-  if (config.loaderFile && typeof defaultLoader === 'undefined') {
+  if (typeof defaultLoader === 'undefined') {
     throw new Error(
       'The loader file must export a default function that returns a string.\nSee more info here: https://nextjs.org/docs/messages/invalid-images-config'
     )