experimental-build-mode compile outputs invalid code

### Link to the code that reproduces this issue https://github.com/AlessioGr/cissue ### To Reproduce 1. Download [my reproduction](https://github.com/AlessioGr/cissue) (or create a new app using create-next-app and apply [this commit](https://github.com/AlessioGr/cissue/commit/c93a71f149fbb7fd832efbf2135060bf1c0cf599)) 2. Create an .env file and add `NEXT_PUBLIC_SERVER_URL='http://localhost:3000'` 3. Run `pnpm next build --experimental-build-mode compile`. This will generate the invalid code 4. Run `pnpm next build --experimental-build-mode generate` - this will inline the environment variables and cause the invalid code to error Important to note: running `pnpm next build` works fine. The issue is the following function (used in a React component to make sure it gets executed during generate step): ```ts const getServerSideURL = () => { let url = process.env.NEXT_PUBLIC_SERVER_URL url = 'http://localhost:3000' return url } ``` Result after `pnpm next build --experimental-build-mode compile`: ```ts children: [ "Get ", (process.env.NEXT_PUBLIC_SERVER_URL, (process.env.NEXT_PUBLIC_SERVER_URL = "http://localhost:3000"), process.env.NEXT_PUBLIC_SERVER_URL), " started by editing ", (0, d.jsx)("code", { children: "app/page.tsx" }), ".", ] ``` Result after `pnpm next build --experimental-build-mode generate`: ```ts children: [ "Get ", ("http://localhost:3000", ("http://localhost:3000" = "http://localhost:3000"), "http://localhost:3000"), " started by editing ", (0, d.jsx)("code", { children: "app/page.tsx" }), ".", ] ``` Invalid code: ```ts "http://localhost:3000" = "http://localhost:3000" ``` => error ```bash alessio@Alessio-Gravili's-MacBook-Pro-(16-inch,-2024)-M4-Max cissue % pnpm next build --experimental-build-mode generate ▲ Next.js 15.5.3 - Environments: .env Creating an optimized production build ... ✓ Collecting page data Inlining static env ... Error occurred pre…