`browser` check for dynamic server module throws error whilst building.

Describe the bug

I have a class that helps me manage specific database items, and this class dynamically imports from either the client side database stuff, or server-side (like administration level database stuff). This totally works fine in npm run dev but when it comes to npm run build, the code doesn't build and throws an error, even though it's behind a browser check and none of the server side stuff is saved, only passed on.

Reproduction

Make functions that dynamically import server side modules or client side modules depending on the browser check and then run that function both on the server and the client.

Logs

[vite-plugin-sveltekit-compile] [vite-plugin-sveltekit-guard] Cannot import $lib/server/firebase.ts into client-side code:
- src/routes/[companyId=firestoreid]/+page.svelte imports
,  - $lib/classes/items/certification.ts imports
,    - $lib/classes/items/item.svelte.ts dynamically imports
   - $lib/server/firebase.ts
[vite-plugin-sveltekit-guard] Cannot import $lib/server/firebase.ts into client-side code:
- src/routes/[companyId=firestoreid]/+page.svelte imports
,  - $lib/classes/items/certification.ts imports
,    - $lib/classes/items/item.svelte.ts dynamically imports
   - $lib/server/firebase.ts
    at follow (file:///Users/x/Developer/x/app/node_modules/@sveltejs/kit/src/exports/vite/graph_analysis/index.js:65:10)
    at follow (file:///Users/x/Developer/x/app/node_modules/@sveltejs/kit/src/exports/vite/graph_analysis/index.js:76:5)
    at follow (file:///Users/x/Developer/x/app/node_modules/@sveltejs/kit/src/exports/vite/graph_analysis/index.js:72:5)
    at follow (file:///Users/x/Developer/x/app/node_modules/@sveltejs/kit/src/exports/vite/graph_analysis/index.js:72:5)
    at follow (file:///Users/x/Developer/x/app/node_modules/@sveltejs/kit/src/exports/vite/graph_analysis/index.js:72:5)
    at Object.check (file:///Users/x/Developer/x/app/node_modules/@sveltejs/kit/src/exports/vite/graph_analysis/index.js:84:4)
    at file:///Users/x/Developer/x/app/node_modules/@sveltejs/kit/src/exports/vite/index.js:575:12
    at Array.forEach (<anonymous>)
    at Object.handler (file:///Users/x/Developer/x/app/node_modules/@sveltejs/kit/src/exports/vite/index.js:570:25)
    at file:///Users/x/Developer/x/app/node_modules/rollup/dist/es/shared/node-entry.js:20812:40

System Info

System:
    OS: macOS 15.5
    CPU: (11) arm64 Apple M3 Pro
    Memory: 106.14 MB / 18.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.13.1 - /usr/local/bin/node
    npm: 10.5.2 - /usr/local/bin/npm
  Browsers:
    Edge: 138.0.3351.83
    Safari: 18.5
  npmPackages:
    @sveltejs/adapter-vercel: ^5.6.2 => 5.6.3 
    @sveltejs/kit: ^2.17.2 => 2.19.1 
    @sveltejs/vite-plugin-svelte: ^4.0.0 => 4.0.4 
    svelte: ^5.28.2 => 5.28.2 
    vite: ^5.4.18 => 5.4.18

Severity

annoyance

Additional Information

No response

Start with the Vite graph analysis entry point shown in node_modules/@sveltejs/kit/src/exports/vite/graph_analysis/index.js and reproduce the issue with npm run build using dynamic imports selected by a browser check. Trace why $lib/server/firebase.ts is considered part of the client graph, then verify that the reported client/server import scenario builds correctly without allowing the server module into client-side code.