Snippet export causes dev script to fail

[jerrythomas]

Describe the bug

bun run dev

$ vite dev
5:10:38 PM [vite] (client) Forced re-optimization of dependencies

  VITE v6.1.1  ready in 250 ms

  ➜  Local:   http://localhost:5173/
  ➜  Network: use --host to expose
  ➜  press h + enter to show help
Error:   Failed to scan for dependencies from entries:
  /Users/Jerry/Developer/Labs/sk-snippet/src/routes/+page.svelte

  ✘ [ERROR] "listItems" is not declared in this file

    script:/Users/Jerry/Developer/Labs/sk-snippet/src/lib/ListItems.svelte?id=0:2:11:
      2 │   export { listItems };
        ╵            ~~~~~~~~~


    at failureErrorWithLog (/Users/Jerry/Developer/Labs/sk-snippet/node_modules/esbuild/lib/main.js:1476:15)
    at /Users/Jerry/Developer/Labs/sk-snippet/node_modules/esbuild/lib/main.js:945:25
    at runOnEndCallbacks (/Users/Jerry/Developer/Labs/sk-snippet/node_modules/esbuild/lib/main.js:1316:45)
    at buildResponseToResult (/Users/Jerry/Developer/Labs/sk-snippet/node_modules/esbuild/lib/main.js:943:7)
    at /Users/Jerry/Developer/Labs/sk-snippet/node_modules/esbuild/lib/main.js:955:9
    at new Promise (<anonymous>)
    at requestCallbacks.on-end (/Users/Jerry/Developer/Labs/sk-snippet/node_modules/esbuild/lib/main.js:954:54)
    at handleRequest (/Users/Jerry/Developer/Labs/sk-snippet/node_modules/esbuild/lib/main.js:647:17)
    at handleIncomingPacket (/Users/Jerry/Developer/Labs/sk-snippet/node_modules/esbuild/lib/main.js:672:7)
    at Socket.readFromStdout (/Users/Jerry/Developer/Labs/sk-snippet/node_modules/esbuild/lib/main.js:600:7)

bun run build
$ vite build
vite v6.1.1 building SSR bundle for production...
✓ 158 modules transformed.
vite v6.1.1 building for production...
✓ 135 modules transformed.
.svelte-kit/output/client/_app/version.json                        0.03 kB │ gzip:  0.05 kB
.svelte-kit/output/client/.vite/manifest.json                      2.91 kB │ gzip:  0.56 kB
.svelte-kit/output/client/_app/immutable/chunks/D0gPaxp9.js        0.03 kB │ gzip:  0.05 kB
.svelte-kit/output/client/_app/immutable/entry/start.CfSTwjUw.js   0.06 kB │ gzip:  0.08 kB
.svelte-kit/output/client/_app/immutable/chunks/DyqcDmWL.js        0.32 kB │ gzip:  0.25 kB
.svelte-kit/output/client/_app/immutable/nodes/0.e8bPOg00.js       0.33 kB │ gzip:  0.24 kB
.svelte-kit/output/client/_app/immutable/chunks/CEAgSoVa.js        0.99 kB │ gzip:  0.56 kB
.svelte-kit/output/client/_app/immutable/nodes/1.BBLo2Zc1.js       1.06 kB │ gzip:  0.61 kB
.svelte-kit/output/client/_app/immutable/chunks/SWgnAoEH.js        2.48 kB │ gzip:  1.36 kB
.svelte-kit/output/client/_app/immutable/chunks/BgrhOOmg.js        3.10 kB │ gzip:  1.47 kB
.svelte-kit/output/client/_app/immutable/nodes/2.BDqgpbH2.js       3.18 kB │ gzip:  1.65 kB
.svelte-kit/output/client/_app/immutable/entry/app.BQLo7ahP.js     6.34 kB │ gzip:  2.98 kB
.svelte-kit/output/client/_app/immutable/chunks/B4LphI0t.js       12.57 kB │ gzip:  5.18 kB
.svelte-kit/output/client/_app/immutable/chunks/CRa4OZW5.js       32.03 kB │ gzip: 12.48 kB
✓ built in 166ms
.svelte-kit/output/server/.vite/manifest.json                   1.93 kB
.svelte-kit/output/server/entries/fallbacks/layout.svelte.js    0.17 kB
.svelte-kit/output/server/internal.js                           0.31 kB
.svelte-kit/output/server/chunks/escaping.js                    0.48 kB
.svelte-kit/output/server/chunks/equality.js                    0.67 kB
.svelte-kit/output/server/entries/pages/_page.svelte.js         0.81 kB
.svelte-kit/output/server/entries/fallbacks/error.svelte.js     1.52 kB
.svelte-kit/output/server/chunks/index.js                       3.06 kB
.svelte-kit/output/server/chunks/exports.js                     6.89 kB
.svelte-kit/output/server/chunks/internal.js                   42.79 kB
.svelte-kit/output/server/index.js                            100.35 kB
✓ built in 465ms

Run npm run preview to preview your production build locally.

> Using @sveltejs/adapter-auto
  Could not detect a supported production environment. See https://svelte.dev/docs/kit/adapters to learn how to configure your app to run on the platform of your choosing
  ✔ done

A subsequent bun run dev works.

Reproduction

How to replicate

git clone git@github.com:jerrythomas/issue-sk-snippet.git
bun i
bun run dev

Playground

The same code works on the playground

https://svelte.dev/playground/9f2ce709c92c451c98221568e8aeaf4e?version=5.20.2

Build works

This runs without errors too!

bun i
bun run build

Logs

System Info

System:
    OS: macOS 15.3.1
    CPU: (16) arm64 Apple M4 Max
    Memory: 614.81 MB / 48.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 23.4.0 - ~/.nvm/versions/node/v23.4.0/bin/node
    npm: 10.9.2 - ~/.nvm/versions/node/v23.4.0/bin/npm
    pnpm: 10.3.0 - /opt/homebrew/bin/pnpm
    bun: 1.2.2 - /opt/homebrew/bin/bun
  Browsers:
    Chrome: 133.0.6943.126
    Safari: 18.3
  npmPackages:
    svelte: ^5.0.0 => 5.20.2

Severity

annoyance

[jerrythomas]

Even though in the reproduction, bun run dev works after the bun run build. However, in my repository I had the snippet in a separate library, and in that repo, bun run build did not solve the bun run dev issue.

I will try to see if I can reproduce the scenario.

[Conduitry]

Does the issue appear with Node? If so, please provide a reproduction using that. Bun has a lot of issues due to incomplete/buggy Node compatibility.