fix(nuxt): fallback to static error page on server error (#6697)

Co-authored-by: Pooya Parsa <pooya@pi0.io>

packages/nuxt/src/core/runtime/nitro/error.ts

@@ -13,7 +13,7 @@ export default <NitroErrorHandler> async function errorhandler (error: H3Error,
     statusCode,
     statusMessage,
     message,
-    description: process.env.NODE_ENV === 'development' && statusCode !== 404
+    stack: process.dev && statusCode !== 404
       ? `<pre>${stack.map(i => `<span class="stack${i.internal ? ' internal' : ''}">${i.text}</span>`).join('\n')}</pre>`
       : '',
     data: error.data
@@ -42,12 +42,23 @@ export default <NitroErrorHandler> async function errorhandler (error: H3Error,
     return
   }
 
-  // HTML response
-  const url = withQuery('/__nuxt_error', errorObject)
-  const html = await $fetch(url).catch((error) => {
-    console.error('[nitro] Error while generating error response', error)
-    return errorObject.statusMessage
-  })
+  // HTML response (via SSR)
+  const isErrorPage = event.req.url?.startsWith('/__nuxt_error')
+  let html = !isErrorPage ? await $fetch(withQuery('/__nuxt_error', errorObject)).catch(() => null) : null
+
+  // Fallback to static rendered error page
+  if (!html) {
+    const { template } = process.dev
+      // @ts-ignore
+      ? await import('@nuxt/ui-templates/templates/error-dev.mjs')
+      // @ts-ignore
+      : await import('@nuxt/ui-templates/templates/error-500.mjs')
+    if (process.dev) {
+      // TODO: Support `message` in template
+      (errorObject as any).description = errorObject.message
+    }
+    html = template(errorObject)
+  }
 
   event.res.setHeader('Content-Type', 'text/html;charset=UTF-8')
   event.res.end(html)

test/basic.test.ts

@@ -181,7 +181,6 @@ describe('errors', () => {
     const error = await res.json()
     delete error.stack
     expect(error).toMatchObject({
-      description: process.env.NUXT_TEST_DEV ? expect.stringContaining('<pre>') : '',
       message: 'This is a custom error',
       statusCode: 500,
       statusMessage: 'Internal Server Error',