Enable inline source maps for swc transform with esbuild

packages/builders/src/apply-swc-transform.ts

@@ -69,10 +69,9 @@ export async function applySwcTransform(
         },
       },
     },
-    // TODO: investigate proper source map support as they
-    // won't even be used in Node.js by default unless we
-    // intercept errors and apply them ourselves
-    sourceMaps: false,
+    // node_modules have invalid source maps often so ignore there
+    // but enable for first party code
+    sourceMaps: filename.includes('node_modules') ? false : 'inline',
     minify: false,
   });
 

packages/core/e2e/utils.ts

@@ -30,7 +30,7 @@ export function hasStepSourceMaps(): boolean {
   // TODO: we need to fix this
   const appName = process.env.APP_NAME as string;
   if (['nextjs-webpack', 'nextjs-turbopack'].includes(appName)) {
-    return false;
+    return true;
   }
 
   // Vercel builds have proper source maps for all other frameworks, EXCEPT sveltekit

packages/core/src/types.ts

@@ -1,4 +1,4 @@
-import { types } from 'node:util';
+import { inspect, types } from 'node:util';
 
 export function getErrorName(v: unknown): string {
   if (types.isNativeError(v)) {
@@ -9,7 +9,9 @@ export function getErrorName(v: unknown): string {
 
 export function getErrorStack(v: unknown): string {
   if (types.isNativeError(v)) {
-    return v.stack ?? '';
+    // Use util.inspect to get the formatted error with source maps applied.
+    // Accessing err.stack directly returns the raw stack without source map resolution.
+    return inspect(v);
   }
   return '';
 }

packages/next/src/loader.ts

@@ -3,19 +3,22 @@ import { transform } from '@swc/core';
 
 // This loader applies the "use workflow"/"use step"
 // client transformation
-export default async function workflowLoader(
+export default function workflowLoader(
   this: {
     resourcePath: string;
+    async: () => (err: Error | null, content?: string, sourceMap?: any) => void;
   },
   source: string | Buffer,
   sourceMap: any
-): Promise<string> {
+) {
+  const callback = this.async();
   const filename = this.resourcePath;
   const normalizedSource = source.toString();
 
   // only apply the transform if file needs it
   if (!normalizedSource.match(/(use step|use workflow)/)) {
-    return normalizedSource;
+    callback(null, normalizedSource, sourceMap);
+    return;
   }
 
   const isTypeScript =
@@ -64,7 +67,7 @@ export default async function workflowLoader(
   }
 
   // Transform with SWC
-  const result = await transform(normalizedSource, {
+  transform(normalizedSource, {
     filename: relativeFilename,
     jsc: {
       parser: {
@@ -94,7 +97,12 @@ export default async function workflowLoader(
     inputSourceMap: sourceMap,
     sourceMaps: true,
     inlineSourcesContent: true,
-  });
-
-  return result.code;
+  }).then(
+    (result) => {
+      callback(null, result.code);
+    },
+    (err) => {
+      callback(err);
+    }
+  );
 }

packages/tsconfig/base.json

@@ -6,8 +6,8 @@
     "declarationMap": true,
     "esModuleInterop": true,
     "forceConsistentCasingInFileNames": true,
-    "sourceMap": true,
-    "inlineSources": false,
+    "sourceMap": false,
+    "inlineSourceMap": true,
     "isolatedModules": true,
     "moduleResolution": "node16",
     "noUnusedLocals": true,

workbench/nextjs-turbopack/next.config.ts

@@ -4,6 +4,9 @@ import { withWorkflow } from 'workflow/next';
 const nextConfig: NextConfig = {
   /* config options here */
   serverExternalPackages: ['@node-rs/xxhash'],
+  experimental: {
+    serverSourceMaps: true,
+  },
 };
 
 // export default nextConfig;

workbench/nextjs-webpack/next.config.ts

@@ -5,7 +5,7 @@ const nextConfig: NextConfig = {
   /* config options here */
   // for easier debugging
   experimental: {
-    serverMinification: false,
+    serverSourceMaps: true,
   },
   serverExternalPackages: ['@node-rs/xxhash'],
 };