Same problem as #13238 when using adapter-vercel

[thebjorn]

Describe the bug

Hi again (I'm assuming you want me to file a new issue, let me know if I should have added to the last one...),

The fix for #13238 worked great for my sample repo, but unfortunately not for my production build. After a bit of searching I figured out that the error

If bundling, conditions should include development or production. If not bundling, conditions or NODE_ENV should include development or production. See https://www.npmjs.com/package/esm-env for tips on setting conditions in popular bundlers and runtimes.

reappears if you switch from adapter-auto to adapter-vercel.

--- a/package.json
+++ b/package.json
@@ -32,13 +32,14 @@
 	},
 	"devDependencies": {
 		"@sveltejs/adapter-auto": "^3.3.1",
-		"@sveltejs/kit": "^2.15.0",
+		"@sveltejs/adapter-vercel": "^5.5.2",
+		"@sveltejs/kit": "^2.15.1",
...

and

--- a/svelte.config.js
+++ b/svelte.config.js
@@ -1,4 +1,5 @@
-import adapter from '@sveltejs/adapter-auto';
+// import adapter from '@sveltejs/adapter-auto';
+import adapter from '@sveltejs/adapter-vercel';
 import { vitePreprocess } from '@sveltejs/vite-plugin-svelte';
...

I have updated the sample repo: https://github.com/thebjorn/sk-sync-bug

Do you want me to file a new issue or do you prefer to re-open this one?

Reproduction

See #13238 with the added diffs from above.

Logs

srv/work/sk-sync-bug❱ pnpm check                                                                                                                                                                                         

> sk-sync-bug@0.0.1 check C:\srv\work\sk-sync-bug
> svelte-kit sync && svelte-check --tsconfig ./tsconfig.json

If bundling, conditions should include development or production. If not bundling, conditions or NODE_ENV should include development or production. See https://www.npmjs.com/package/esm-env for tips on setting conditions in popular bundlers and runtimes.

====================================
Loading svelte-check in workspace: c:\srv\work\sk-sync-bug
Getting Svelte diagnostics...

If bundling, conditions should include development or production. If not bundling, conditions or NODE_ENV should include development or production. See https://www.npmjs.com/package/esm-env for tips on setting conditions in popular bundlers and runtimes.
====================================
svelte-check found 0 errors and 0 warnings

srv/work/sk-sync-bug❱

System Info

System:
    OS: Windows 11 10.0.22631
    CPU: (48) x64 AMD Ryzen Threadripper 3960X 24-Core Processor 
    Memory: 41.83 GB / 63.88 GB
  Binaries:
    Node: 22.12.0 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.22 - ~\AppData\Roaming\npm\yarn.CMD
    npm: 10.9.2 - C:\Program Files\nodejs\npm.CMD
    pnpm: 9.15.1 - ~\AppData\Local\pnpm\pnpm.CMD
    bun: 1.1.41 - ~\AppData\Roaming\npm\bun.CMD
  Browsers:
    Edge: Chromium (127.0.2651.74)
    Internet Explorer: 11.0.22621.3527
  npmPackages:
    @sveltejs/adapter-auto: ^3.3.1 => 3.3.1
    @sveltejs/adapter-vercel: ^5.5.2 => 5.5.2
    @sveltejs/kit: ^2.15.1 => 2.15.1
    @sveltejs/package: ^2.3.7 => 2.3.7
    @sveltejs/vite-plugin-svelte: ^5.0.3 => 5.0.3
    svelte: ^5.16.1 => 5.16.1
    vite: ^6.0.7 => 6.0.7

Severity

annoyance

Additional Information

No response

[eltigerchino]

This happens because the Vercel adapter imports the VERSION variable from the SvelteKit package which imports from esm-env.

kit/packages/kit/src/exports/index.js

Lines 2 to 4 in 9fbfb22

	import { BROWSER, DEV } from 'esm-env';
	export { VERSION } from '../version.js';

Don't think we can apply the same fix as #13244 since we need the DEV variable for the other helpers in the file.
cc: @benmccann

[thebjorn]

It's not the easiest problem to isolate... maybe having a --verbose flag to svelte-kit sync would help finding where it originates...

[benmccann]

I think I'll just release a new version of esm-env without the warning