adapter-vercel — ERROR: Top-level await is currently not supported with the "cjs" output format

[acarl005]

Describe the bug

When building the app with @sveltejs/adapter-vercel, and when I use top-level await in my server routes, I get this error:

.svelte-kit/output/server/entries/endpoints/helloworld.js:1:0: ERROR: Top-level await is currently not supported with the "cjs" output format

However, my package.json specifies "type": "module", but it still thinks I'm using cjs when I'm not.

Reproduction

https://stackblitz.com/edit/sveltejs-kit-template-default-qgneqz?file=src/routes/helloworld.js

Then, run npm run build

Logs

npm run build

.svelte-kit/output/server/entries/endpoints/helloworld.js:1:0: ERROR: Top-level await is currently not supported with the "cjs" output format

System Info

See my StackBlitz link

https://stackblitz.com/edit/sveltejs-kit-template-default-qgneqz?file=svelte.config.js,src%2Froutes%2Fhelloworld.js&terminal=dev

Severity

serious, but I can work around it

Additional Information

I'm using the recommended setup for a new sveltekit app, for which ECMA modules are encourages. That being the case, I believe the module features which are now built into node.js, like top-level await, should be usable.

[Rich-Harris]

Ah, I forgot there was a reason for holding off on merging #4967. #4969 would fix this, but it causes certain builds to hang in a way that I don't currently understand.

For the time being, I'd recommend pinning to 1.0.0-next.52 or 51.

[acarl005]

Thanks for the response, Rich! Pinning to 1.0.0-next.52 worked.

[furudean]

@Rich-Harris This seems to still happen with @sveltejs/adapter-vercel@1.0.0-next.56 and @sveltejs/kit@1.0.0-next.345

> Build failed with 1 error:
.svelte-kit/output/server/entries/matchers/entry.js:6:20: ERROR: Top-level await is currently not supported with the "cjs" output format
.svelte-kit/output/server/entries/matchers/entry.js:6:20: ERROR: Top-level await is currently not supported with the "cjs" output format
    at failureErrorWithLog (/Users/meri/Code/stemwringer/node_modules/esbuild/lib/main.js:1600:15)
    at /Users/meri/Code/stemwringer/node_modules/esbuild/lib/main.js:1246:28
    at runOnEndCallbacks (/Users/meri/Code/stemwringer/node_modules/esbuild/lib/main.js:1159:65)
    at buildResponseToResult (/Users/meri/Code/stemwringer/node_modules/esbuild/lib/main.js:1244:7)
    at /Users/meri/Code/stemwringer/node_modules/esbuild/lib/main.js:1353:14
    at /Users/meri/Code/stemwringer/node_modules/esbuild/lib/main.js:663:9
    at handleIncomingPacket (/Users/meri/Code/stemwringer/node_modules/esbuild/lib/main.js:760:9)
    at Socket.readFromStdout (/Users/meri/Code/stemwringer/node_modules/esbuild/lib/main.js:629:7)
    at Socket.emit (node:events:527:28)
    at Socket.emit (node:domain:475:12)

[furudean]

Could this issue be reopened? @Rich-Harris

I think #4967 being merged is what caused this to show up again.