fix(nextjs): Strip sourceMappingURL comments after deleting source maps in turbopack builds

[chargome]

When withSentryConfig is used with Next.js 16 + turbopack, the SDK auto-enables productionBrowserSourceMaps: true and deleteSourcemapsAfterUpload: true. After the build, .map files are deleted, but the corresponding //# sourceMappingURL=... comments remain in the JS chunks.

When browsers (e.g. Chrome DevTools) request these nonexistent .map files, Next.js 16 (turbopack) does not return a 404. Instead, the request falls through to the app router, where catch-all routes handle it. Since middleware matchers typically exclude _next paths, middleware does not run for
these requests, causing SSR failures for middleware-dependent features (e.g. Clerk's auth() throws because clerkMiddleware() headers are absent).

This fix strips dangling sourceMappingURL comments from client JS/CSS files after source map deletion, but only for turbopack builds where the issue manifests.

• Scoped to turbopack only to minimize blast radius
• Runs after deleteArtifacts() in the post-build hook
• Handles JS, MJS, CJS, and CSS files recursively in static/

closes#19600

[github-actions]

size-limit report 📦

⚠️Warning: Base artifact is not the latest one, because the latest workflow run is not done yet. This may lead to incorrect results. Try to re-run all tests to get up to date results.

Path	Size	% Change	Change
@sentry/browser	25.64 kB	-	-
@sentry/browser - with treeshaking flags	24.14 kB	-	-
@sentry/browser (incl. Tracing)	42.62 kB	-	-
@sentry/browser (incl. Tracing, Profiling)	47.28 kB	-	-
@sentry/browser (incl. Tracing, Replay)	81.42 kB	-	-
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags	71 kB	-	-
@sentry/browser (incl. Tracing, Replay with Canvas)	86.12 kB	-	-
@sentry/browser (incl. Tracing, Replay, Feedback)	98.37 kB	-	-
@sentry/browser (incl. Feedback)	42.45 kB	-	-
@sentry/browser (incl. sendFeedback)	30.31 kB	-	-
@sentry/browser (incl. FeedbackAsync)	35.36 kB	-	-
@sentry/browser (incl. Metrics)	26.92 kB	-	-
@sentry/browser (incl. Logs)	27.07 kB	-	-
@sentry/browser (incl. Metrics & Logs)	27.74 kB	-	-
@sentry/react	27.39 kB	-	-
@sentry/react (incl. Tracing)	44.95 kB	-	-
@sentry/vue	30.08 kB	-	-
@sentry/vue (incl. Tracing)	44.48 kB	-	-
@sentry/svelte	25.66 kB	-	-
CDN Bundle	28.27 kB	-	-
CDN Bundle (incl. Tracing)	43.5 kB	-	-
CDN Bundle (incl. Logs, Metrics)	29.13 kB	-	-
CDN Bundle (incl. Tracing, Logs, Metrics)	44.34 kB	-	-
CDN Bundle (incl. Replay, Logs, Metrics)	68.2 kB	-	-
CDN Bundle (incl. Tracing, Replay)	80.32 kB	-	-
CDN Bundle (incl. Tracing, Replay, Logs, Metrics)	81.22 kB	-	-
CDN Bundle (incl. Tracing, Replay, Feedback)	85.86 kB	-	-
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics)	86.76 kB	-	-
CDN Bundle - uncompressed	82.56 kB	-	-
CDN Bundle (incl. Tracing) - uncompressed	128.5 kB	-	-
CDN Bundle (incl. Logs, Metrics) - uncompressed	85.43 kB	-	-
CDN Bundle (incl. Tracing, Logs, Metrics) - uncompressed	131.37 kB	-	-
CDN Bundle (incl. Replay, Logs, Metrics) - uncompressed	209.06 kB	-	-
CDN Bundle (incl. Tracing, Replay) - uncompressed	245.35 kB	-	-
CDN Bundle (incl. Tracing, Replay, Logs, Metrics) - uncompressed	248.21 kB	-	-
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed	258.26 kB	-	-
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics) - uncompressed	261.11 kB	-	-
@sentry/nextjs (client)	47.37 kB	-	-
@sentry/sveltekit (client)	43.07 kB	-	-
@sentry/node-core	56.34 kB	+0.02%	+11 B 🔺
@sentry/node	173.23 kB	+0.03%	+48 B 🔺
@sentry/node - without tracing	96.35 kB	+0.01%	+5 B 🔺
@sentry/aws-serverless	113.34 kB	+0.01%	+7 B 🔺

View base workflow run

[masterjanic]

@chargome This is causing heavy issues when Subresource Integrity (SRI) is enabled, because it modifies the files after build and the generated hashes don't match anymore!