fix(nitro): Skip source map upload in nitro-prerender nested build

Nitro spawns a nested Nitro instance for prerendering with the user's
`modules` array re-installed, which caused the Sentry module to run
twice and upload source maps + create a release twice per build.

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

Author: logaretm

packages/nitro/src/sourceMaps.ts

@@ -13,6 +13,12 @@ export function setupSourceMaps(nitro: Nitro, options?: SentryNitroOptions, sent
     return;
   }
 
+  // Nitro spawns a nested Nitro instance for prerendering with the user's `modules` re-installed.
+  // Uploading here would double-upload source maps and create a duplicate release.
+  if (nitro.options.preset === 'nitro-prerender') {
+    return;
+  }
+
   // Respect user's explicit disable
   if (options?.sourcemaps?.disable === true) {
     return;

packages/nitro/test/sourceMaps.test.ts

@@ -274,6 +274,18 @@ describe('setupSourceMaps', () => {
     expect(hookFn).not.toHaveBeenCalled();
   });
 
+  it('does not register hook in nitro-prerender preset', () => {
+    const hookFn = vi.fn();
+    const nitro = {
+      options: { dev: false, preset: 'nitro-prerender', output: { serverDir: '/output/server' } },
+      hooks: { hook: hookFn },
+    } as any;
+
+    setupSourceMaps(nitro);
+
+    expect(hookFn).not.toHaveBeenCalled();
+  });
+
   it('registers compiled hook in production mode', () => {
     const hookFn = vi.fn();
     const nitro = {