fix: added temp error workaround

packages/next/src/server/base-server.ts

@@ -109,6 +109,7 @@ import {
 import { NEXT_QUERY_PARAM_PREFIX } from '../lib/constants'
 import { isRouteMatch } from './future/route-matches/route-match'
 import { NextRequestAdapter } from './web/spec-extension/adapters/next-request'
+import { NotFoundError } from './future/route-modules/helpers/render-result-to-response'
 
 export type FindComponentsResult = {
   components: LoadComponentsReturnType
@@ -1794,12 +1795,24 @@ export default abstract class Server<ServerOptions extends Options = Options> {
 
           // Handle the request using the module.
           const request = NextRequestAdapter.fromBaseNextRequest(req)
-          const response = await module.handle(request, context)
 
-          // Send the response now that we have copied it into the cache.
-          await sendResponse(req, res, response)
+          try {
+            const response = await module.handle(request, context)
 
-          return null
+            // Send the response now that we have copied it into the cache.
+            await sendResponse(req, res, response)
+
+            return null
+          } catch (err) {
+            if (NotFoundError.isNotFoundError(err)) {
+              // If we couldn't find the page, we should return null so that
+              // the legacy render method will be used.
+              return { value: null, revalidate: err.metadata.revalidate }
+            }
+
+            // This was an unexpected error, so we should throw it again.
+            throw err
+          }
         }
       } else {
         // If we didn't match a page, we should fallback to using the legacy

packages/next/src/server/future/route-modules/helpers/render-result-to-response.ts

@@ -3,6 +3,7 @@ import type { RouteDefinition } from '../../route-definitions/route-definition'
 import type { Redirect } from '../../../../../types'
 import type RenderResult from '../../../render-result'
 import type { NextRequest } from '../../../web/spec-extension/request'
+import type { RenderResultMetadata } from '../../../render-result'
 
 import fresh from 'next/dist/compiled/fresh'
 import { normalizeRepeatedSlashes } from '../../../../shared/lib/utils'
@@ -27,6 +28,16 @@ type RenderResultToResponseModule = {
   generateEtags: boolean | undefined
 }
 
+export class NotFoundError {
+  public readonly digest = 'NEXT_PAGES_NOT_FOUND'
+
+  constructor(public readonly metadata: RenderResultMetadata) {}
+
+  public static isNotFoundError(error: any): error is NotFoundError {
+    return error?.digest === 'NEXT_PAGES_NOT_FOUND'
+  }
+}
+
 /**
  * Converts a `RenderResult` into a `Response` object.
  *
@@ -127,7 +138,12 @@ export async function renderResultToResponse(
 
   // If this is a not found, we can return the result immediately.
   if (metadata.isNotFound) {
-    throw new Error("Invariant: 'isNotFound' should never be true here")
+    // TODO: re-enable this once error handling is inside the module
+    // throw new Error("Invariant: 'isNotFound' should never be true here")
+
+    // NOTE: this is a temporary workaround until we can get the error handling
+    // inside the module. This will trigger the not found page.
+    throw new NotFoundError(metadata)
   }
 
   // Get and set the content type on the response.

packages/next/src/server/future/route-modules/pages/module.ts

@@ -142,14 +142,16 @@ export class PagesRouteModule extends RouteModule<
     )
   }
 
-  public render(
+  public async render(
     req: IncomingMessage,
     res: ServerResponse,
     pathname: string,
     query: NextParsedUrlQuery,
     renderOpts: RenderOpts
   ): Promise<RenderResult> {
-    return renderToHTML(req, res, pathname, query, renderOpts)
+    const result = await renderToHTML(req, res, pathname, query, renderOpts)
+
+    return result
   }
 }