ref(nextjs): Apply uncaught exception fix (#6138) only when middleware is configured

Author: Luca Forstner

packages/nextjs/src/config/loaders/prefixLoader.ts

@@ -5,22 +5,24 @@ import { LoaderThis } from './types';
 
 type LoaderOptions = {
   distDir: string;
+  hasMiddleware: boolean;
 };
 
 /**
  * Inject templated code into the beginning of a module.
  */
 export default function prefixLoader(this: LoaderThis<LoaderOptions>, userCode: string): string {
   // We know one or the other will be defined, depending on the version of webpack being used
-  const { distDir } = 'getOptions' in this ? this.getOptions() : this.query;
+  const { distDir, hasMiddleware } = 'getOptions' in this ? this.getOptions() : this.query;
 
   const templatePath = path.resolve(__dirname, '../templates/prefixLoaderTemplate.js');
   // make sure the template is included when runing `webpack watch`
   this.addDependency(templatePath);
 
-  // Fill in the placeholder
+  // Fill in placehoolders
   let templateCode = fs.readFileSync(templatePath).toString();
   templateCode = templateCode.replace('__DIST_DIR__', distDir.replace(/\\/g, '\\\\'));
+  templateCode = templateCode.replace('__HAS_MIDDLEWARE__', hasMiddleware ? 'true' : 'false');
 
   return `${templateCode}\n${userCode}`;
 }

packages/nextjs/src/config/templates/prefixLoaderTemplate.ts

@@ -1,5 +1,9 @@
+declare const __HAS_MIDDLEWARE__: boolean;
+
 // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access, @typescript-eslint/no-explicit-any
 (global as any).__rewriteFramesDistDir__ = '__DIST_DIR__';
+// eslint-disable-next-line @typescript-eslint/no-unsafe-member-access, @typescript-eslint/no-explicit-any
+(global as any).__hasMiddleware__ = __HAS_MIDDLEWARE__;
 
 // We need this to make this file an ESM module, which TS requires when using `isolatedModules`, but it doesn't affect
 // the end result - Rollup recognizes that it's a no-op and doesn't include it when building our code.

packages/nextjs/src/config/webpack.ts

@@ -58,6 +58,13 @@ export function constructWebpackConfigFunction(
     }
 
     if (isServer) {
+      const pagesDir = newConfig.resolve?.alias?.['private-next-pages'] as string;
+
+      const middlewareJsPath = path.join(pagesDir, '..', 'middleware.js');
+      const middlewareTsPath = path.join(pagesDir, '..', 'middleware.ts');
+
+      const hasMiddleware = fs.existsSync(middlewareJsPath) || fs.existsSync(middlewareTsPath);
+
       newConfig.module = {
         ...newConfig.module,
         rules: [
@@ -72,6 +79,7 @@ export function constructWebpackConfigFunction(
                 loader: path.resolve(__dirname, 'loaders/prefixLoader.js'),
                 options: {
                   distDir: userNextConfig.distDir || '.next',
+                  hasMiddleware,
                 },
               },
             ],
@@ -80,8 +88,6 @@ export function constructWebpackConfigFunction(
       };
 
       if (userSentryOptions.autoInstrumentServerFunctions !== false) {
-        const pagesDir = newConfig.resolve?.alias?.['private-next-pages'] as string;
-
         // Default page extensions per https://github.com/vercel/next.js/blob/f1dbc9260d48c7995f6c52f8fbcc65f08e627992/packages/next/server/config-shared.ts#L161
         const pageExtensions = userNextConfig.pageExtensions || ['tsx', 'ts', 'jsx', 'js'];
         const pageExtensionRegex = pageExtensions.map(escapeStringForRegex).join('|');

packages/nextjs/src/index.server.ts

@@ -19,7 +19,10 @@ export { captureUnderscoreErrorException } from './utils/_error';
 // because or SSR of next.js we can only use this.
 export { ErrorBoundary, showReportDialog, withErrorBoundary } from '@sentry/react';
 
-type GlobalWithDistDir = typeof global & { __rewriteFramesDistDir__: string };
+type GlobalWithBuildTimeConfiguration = typeof global & {
+  __rewriteFramesDistDir__: string;
+  __hasMiddleware__: boolean;
+};
 const domain = domainModule as typeof domainModule & { active: (domainModule.Domain & Carrier) | null };
 
 // Exporting this constant means we can compute it without the linter complaining, even if we stop directly using it in
@@ -104,7 +107,7 @@ function addServerIntegrations(options: NextjsOptions): void {
 
   // This value is injected at build time, based on the output directory specified in the build config. Though a default
   // is set there, we set it here as well, just in case something has gone wrong with the injection.
-  const distDirName = (global as GlobalWithDistDir).__rewriteFramesDistDir__ || '.next';
+  const distDirName = (global as GlobalWithBuildTimeConfiguration).__rewriteFramesDistDir__ || '.next';
   // nextjs always puts the build directory at the project root level, which is also where you run `next start` from, so
   // we can read in the project directory from the currently running process
   const distDirAbsPath = path.resolve(process.cwd(), distDirName);
@@ -118,10 +121,12 @@ function addServerIntegrations(options: NextjsOptions): void {
   });
   integrations = addOrUpdateIntegration(defaultRewriteFramesIntegration, integrations);
 
-  const nativeBehaviourOnUncaughtException = new Integrations.OnUncaughtException();
-  integrations = addOrUpdateIntegration(nativeBehaviourOnUncaughtException, integrations, {
-    _options: { exitEvenIfOtherHandlersAreRegistered: false },
-  });
+  if ((global as GlobalWithBuildTimeConfiguration).__hasMiddleware__) {
+    const nativeBehaviourOnUncaughtException = new Integrations.OnUncaughtException();
+    integrations = addOrUpdateIntegration(nativeBehaviourOnUncaughtException, integrations, {
+      _options: { exitEvenIfOtherHandlersAreRegistered: false },
+    });
+  }
 
   if (hasTracingEnabled(options)) {
     const defaultHttpTracingIntegration = new Integrations.Http({ tracing: true });