fix(pages): preserve missing page props on errors

packages/vinext/src/entries/pages-client-entry.ts

@@ -65,6 +65,7 @@ export async function generateClientEntry(
   const apiRoutes = await apiRouter(pagesDir, nextConfig?.pageExtensions, fileMatcher);
 
   const appFilePath = findFileWithExts(pagesDir, "_app", fileMatcher);
+  const errorFilePath = findFileWithExts(pagesDir, "_error", fileMatcher);
   const hasApp = appFilePath !== null;
   const appPrefetchRoutes = options.appPrefetchRoutes ?? [];
   const pagesPrefetchRoutes: VinextPagesLinkPrefetchRoute[] = [
@@ -102,6 +103,11 @@ export async function generateClientEntry(
     // lgtm[js/bad-code-sanitization]
     return `  ${JSON.stringify(nextFormatPattern)}: () => import(${JSON.stringify(absPath)})`;
   });
+  loaderEntries.push(
+    errorFilePath !== null
+      ? `  "/_error": () => import(${JSON.stringify(errorFilePath)})`
+      : '  "/_error": () => import("next/error")',
+  );
 
   const appFileBase = appFilePath ?? undefined;
 

packages/vinext/src/entries/pages-server-entry.ts

@@ -95,7 +95,7 @@ export async function generateServerEntry(
   const errorImportCode =
     errorFilePath !== null
       ? `import * as ErrorPageModule from ${JSON.stringify(errorFilePath)};`
-      : `const ErrorPageModule = null;`;
+      : `import * as ErrorPageModule from "next/error";`;
 
   // Serialize i18n config for embedding in the server entry
   const i18nConfigJson = nextConfig?.i18n
@@ -301,16 +301,14 @@ export const pageRoutes = [
 ${pageRouteEntries.join(",\n")}
 ];
 const _pageRouteTrie = _buildRouteTrie(pageRoutes);
-const _errorPageRoute = ErrorPageModule
-  ? {
-      pattern: "/_error",
-      patternParts: ["_error"],
-      isDynamic: false,
-      params: [],
-      module: ErrorPageModule,
-      filePath: ${errorAssetPathJson},
-    }
-  : null;
+const _errorPageRoute = {
+  pattern: "/_error",
+  patternParts: ["_error"],
+  isDynamic: false,
+  params: [],
+  module: ErrorPageModule,
+  filePath: ${errorAssetPathJson},
+};
 
 const apiRoutes = [
 ${apiRouteEntries.join(",\n")}