fix(nitro): Default to hidden source maps when Sentry enables them

Previously when users didn't set `sourcemap`, we set it to `true`, which
causes Nitro/Vite to append `//# sourceMappingURL=` to each output file,
publicly exposing sourcemap references. Switch to `'hidden'` so .map files
are still emitted (and uploaded/deleted by Sentry) without the public
reference comment.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: logaretm

packages/nitro/src/sourceMaps.ts

@@ -156,13 +156,15 @@ export function configureSourcemapSettings(
       console.log('[@sentry/nitro] Source maps are already enabled. Sentry will upload them for error unminification.');
     }
   } else {
-    // User did not explicitly set sourcemap — enable it for Sentry
-    config.sourcemap = true;
+    // User did not explicitly set sourcemap, enable hidden source maps for Sentry.
+    // Nitro types `sourcemap` as `boolean`, but it forwards the value to Vite which supports `'hidden'`.
+    // `'hidden'` emits .map files without adding a `//# sourceMappingURL=` comment to the output, avoiding public exposure.
+    (config as { sourcemap?: unknown }).sourcemap = 'hidden';
     sentryEnabledSourcemaps = true;
     if (moduleOptions?.debug) {
       // eslint-disable-next-line no-console
       console.log(
-        '[@sentry/nitro] Enabled source map generation for Sentry. Source map files will be deleted after upload.',
+        '[@sentry/nitro] Enabled hidden source map generation for Sentry. Source map files will be deleted after upload.',
       );
     }
   }

packages/nitro/test/sourceMaps.test.ts

@@ -179,11 +179,11 @@ describe('getPluginOptions', () => {
 });
 
 describe('configureSourcemapSettings', () => {
-  it('enables sourcemap generation on the config', () => {
+  it('enables hidden sourcemap generation on the config', () => {
     const config: NitroConfig = {};
     const result = configureSourcemapSettings(config);
 
-    expect(config.sourcemap).toBe(true);
+    expect(config.sourcemap).toBe('hidden');
     expect(result.sentryEnabledSourcemaps).toBe(true);
   });
 
@@ -244,7 +244,7 @@ describe('configureSourcemapSettings', () => {
     const config: NitroConfig = {};
     configureSourcemapSettings(config, { sourcemaps: { disable: 'disable-upload' } });
 
-    expect(config.sourcemap).toBe(true);
+    expect(config.sourcemap).toBe('hidden');
   });
 });