[BUG]: Next.js config plugin crashes middleware (edge runtime)

[Sgouws]

varlock version

0.5.0, @varlock/nextjs-integration 0.2.3

Problem

Using varlockNextConfigPlugin() crashes any Next.js app that has middleware. Every request returns 500:

⨯ Error [TypeError]: Native module not found: varlock/env
    at <unknown> (.next/server/edge-runtime-webpack.js:3:11)

Removing the plugin and using only the @next/env override works fine.

Root cause

The plugin injects patch-next-runtime.js into both the Node.js server runtime and the edge runtime (edge-runtime-webpack.js). That patch file does require('varlock/env'), which works in Node.js but fails in the edge sandbox since it only allows native modules.

The _edgeRuntime parameter in injectVarlockInitIntoWebpackRuntime() is accepted but never used — edge gets the exact same patch as Node.js.

Reproduction

1. Next.js 15 project with a middleware.ts (Clerk, Auth.js, or even a bare NextResponse.next())
2. Add the @next/env override and varlockNextConfigPlugin() per the docs
3. Start the dev server, navigate to any page, get a 500

Workaround

Use the @next/env override without the config plugin. Loses leak detection and ENV import support, but env loading and validation work fine.

System Info

Next.js: 15.5.12
Node: v25.2.1
macOS arm64

[theoephraim]

I’m just in the middle of totally reworking the next integration, including full turbo support!

so will (try to) make sure this is fixed too. The matrix of possibilities of next version, runtime, etc and the lack of a real plugin system make it quite challenging.

[theoephraim]

@Sgouws - try these preview packages (install both varlock and the next integration using the urls)

I think everything is totally working in next 15/16, webpack/turbopack, node/edge - but would be great to have some confirmation from non test projects.

[Sgouws]

@theoephraim Tested the packages from PR #393 against our Next.js 15.5.12 project with Clerk middleware. Dev server, middleware compilation, and production build all pass. No more Native module not found: varlock/env error.

Thanks for the quick fix!

[theoephraim]

Awesome - thanks for testing! Supporting all this without next having a real plugin system is a HUGE pain. Glad to hear it is working.

Will get this pushed out today.