"Cannot import into client-side code" errors are incredibly difficult to debug

[MaddyGuthridge]

Describe the bug

In my project, I have inadvertently imported some server-side code into my front-end code. However, the error message gives no indication of where the import has come from, meaning I have to hunt through hundreds of files to try to find the offending import statement.

Reproduction

1. Import code from $lib/server/... into client-side code.
2. Notice that the error gives no indication of where the incorrect import occurs.

Logs

10:21:01 pm [vite] Internal server error: Cannot import $lib/server/data/dataDir.ts into client-side code
      at LoadPluginContext.load (file:///home/maddy/Source/Minifolio/node_modules/@sveltejs/kit/src/exports/vite/index.js:418:12)
      at PluginContainer.load (file:///home/maddy/Source/Minifolio/node_modules/vite/dist/node/chunks/dep-BWSbWtLw.js:49064:17)
      at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
      at async loadAndTransform (file:///home/maddy/Source/Minifolio/node_modules/vite/dist/node/chunks/dep-BWSbWtLw.js:51869:22)
      at async viteTransformMiddleware (file:///home/maddy/Source/Minifolio/node_modules/vite/dist/node/chunks/dep-BWSbWtLw.js:61881:24)

System Info

System:
    OS: Linux 6.12 Fedora Linux 41 (Workstation Edition)
    CPU: (12) x64 Intel(R) Core(TM) i7-10750H CPU @ 2.60GHz
    Memory: 50.80 GB / 62.41 GB
    Container: Yes
    Shell: 5.9 - /usr/bin/zsh
  Binaries:
    Node: 22.12.0 - /run/user/1000/fnm_multishells/344514_1735730898683/bin/node
    npm: 10.9.0 - /run/user/1000/fnm_multishells/344514_1735730898683/bin/npm
    bun: 1.1.34 - ~/.bun/bin/bun
  Browsers:
    Chrome: 131.0.6778.204
  npmPackages:
    @sveltejs/adapter-node: ^5.0.1 => 5.2.9 
    @sveltejs/kit: ^2.5.27 => 2.9.0 
    @sveltejs/vite-plugin-svelte: ^4.0.0 => 4.0.0 
    svelte: ^5.0.0 => 5.1.12 
    vite: ^5.4.6 => 5.4.10

Severity

annoyance

Additional Information

I understand that I have got a bug in my code somewhere. The issue is that the error's trace-back makes it impossible to quickly determine where the bug is, which is incredibly frustrating. Showing me which file the bad import occurs within would be very helpful.

[TheBeachMaster]

This and this #5937 are so annoying and I wish the Svelte team would do us a solid and provide usable stack-traces...