Fix global-error for nested routes (#60539)

## What

This fixes when the deep nested routes throws a client side error, it
can still be caught by the `global-error.js`

## How

We should always resolve global-error from root app directory instead of
current route's layout. Also fixed a bad test before where the
gloabl-error.js is not located correctly


Fixes #53756
Closes NEXT-1760

packages/next/src/build/webpack/loaders/next-app-loader.ts

@@ -198,7 +198,7 @@ async function createTreeCodeFromPath(
   const pages: string[] = []
 
   let rootLayout: string | undefined
-  let globalError: string = defaultGlobalErrorPath
+  let globalError: string | undefined
 
   async function resolveAdjacentParallelSegments(
     segmentPath: string
@@ -356,20 +356,20 @@ async function createTreeCodeFromPath(
         )?.[1]
         rootLayout = layoutPath
 
-        if (isDefaultNotFound && !layoutPath) {
+        if (isDefaultNotFound && !layoutPath && !rootLayout) {
           rootLayout = defaultLayoutPath
           definedFilePaths.push(['layout', rootLayout])
         }
+      }
 
-        if (layoutPath) {
+      if (!globalError) {
         const resolvedGlobalErrorPath = await resolver(
-            `${path.dirname(layoutPath)}/${GLOBAL_ERROR_FILE_TYPE}`
+          `${appDirPrefix}/${GLOBAL_ERROR_FILE_TYPE}`
         )
         if (resolvedGlobalErrorPath) {
           globalError = resolvedGlobalErrorPath
         }
       }
-      }
 
       let parallelSegmentKey = Array.isArray(parallelSegment)
         ? parallelSegment[0]
@@ -468,7 +468,7 @@ async function createTreeCodeFromPath(
     treeCode: `${treeCode}.children;`,
     pages: `${JSON.stringify(pages)};`,
     rootLayout,
-    globalError,
+    globalError: globalError ?? defaultGlobalErrorPath,
   }
 }
 

test/e2e/app-dir/global-error/basic/app/global-error.js

@@ -12,3 +12,6 @@ export default function GlobalError({ error }) {
     </html>
   )
 }
+
+// for inspecting purpose
+GlobalError.displayName = 'GlobalError'

test/e2e/app-dir/global-error/basic/app/nested/layout.js

@@ -0,0 +1,3 @@
+export default function NestedLayout({ children }) {
+  return <div>{children}</div>
+}

test/e2e/app-dir/global-error/basic/app/nested/nested/page.js

@@ -0,0 +1,19 @@
+'use client'
+
+import { useEffect, useState } from 'react'
+
+export default function ClientPage() {
+  const [bad, setBad] = useState(false)
+
+  useEffect(() => {
+    setTimeout(() => {
+      setBad(true)
+    })
+  }, [])
+
+  if (bad) {
+    throw Error('nested error')
+  }
+
+  return <p>client page</p>
+}

test/e2e/app-dir/global-error/basic/index.test.ts

@@ -79,5 +79,17 @@ createNextDescribe(
         )
       }
     })
+
+    it('should catch the client error thrown in the nested routes', async () => {
+      const browser = await next.browser('/nested/nested')
+      if (isNextDev) {
+        await testDev(browser, /Error: nested error/)
+      } else {
+        expect(await browser.elementByCss('h1').text()).toBe('Global Error')
+        expect(await browser.elementByCss('#error').text()).toBe(
+          'Global error: nested error'
+        )
+      }
+    })
   }
 )