Static JS file "was not found" on intial page request (but ok after subsequent requests)

Describe the bug

I am getting some unexpected behavior involving use of an external (non svelte) that is intended to be invoked after svelte-kit renders the initial page.

In my src/routes/index.svelte file I have the following:

<svelte:head>
	<script src="/js/index.bundle.js"></script>
</svelte:head>
// and then in this same .svelte file also a <script> , some html content and a <style> section ) 

The JS file I have bundled separately (outside of svelte land) and just needs to run after my initial svelte powered index runs; I’m not sure if there is a better way to wait for svelte to finish rendering but currently I just am using a 500ms delay in this particular external script.

Anyway, that is beside the point - the main problem is this error on the first request I make (see log)

(but actually I just tested the production build ie- yarn build and noticed there were no such problems; so evidently this only occurs in dev mode. And another reason this isn’t such a big deal is even in dev mode the bundle ‘was not found’ msges go away on subsequent requests; ie- i just have to reload the page once and my external bundle works as intended… so just thought I would share this; not sure why that initial request is not working as intended I supppose the only inconvenience is that I have to remind other collaborators on my project to refresh the index page once it loads initially after starting in dev mode)

Reproduction

😕

Logs

drs@mypc:/dev/project$ yarn dev
yarn run v1.22.10
warning package.json: No license field
$ svelte-kit dev --port 3027

  SvelteKit v1.0.0-next.115

  local:   http://localhost:3027
  network: not exposed
  network: not exposed
  network: not exposed

  Use --host to expose server to other devices on this network

## (idles here until requesting my index page ie- localhost:3027/ aka ./src/routes/index.svelte )

warn - You have enabled the JIT engine which is currently in preview.
warn - Preview features are not covered by semver, may introduce breaking changes, and can change at any time.
[svelte-preprocess] The file  "/js/index.bundle.js" was not found.
[vite-plugin-svelte] /dev/project/src/routes/index.svelte:96:1 Unused CSS selector "p"
[svelte-preprocess] The file  "/js/index.bundle.js" was not found.

System Info

System:
    OS: Linux 5.11 Ubuntu 20.04.2 LTS (Focal Fossa)
    CPU: (24) x64 AMD Ryzen 9 3900X 12-Core Processor
    Memory: 831.66 MB / 15.58 GB
    Container: Yes
    Shell: 5.0.17 - /bin/bash
  Binaries:
    Node: 14.17.4 - ~/n/bin/node
    Yarn: 1.22.10 - ~/n/bin/yarn
    npm: 6.14.14 - ~/n/bin/npm
  Browsers:
    Firefox: 90.0.2
  npmPackages:
    @sveltejs/adapter-node: ^1.0.0-next.26 => 1.0.0-next.26 
    @sveltejs/adapter-static: ^1.0.0-next.13 => 1.0.0-next.13 
    @sveltejs/kit: next => 1.0.0-next.115 
    svelte: ^3.34.0 => 3.38.2

Severity

annoyance

Additional Information

No response

[Rich-Harris]

Can’t reproduce this, and the original comment put ‘😕’ in place of a repro so I’ll close this.

Note that script tags in a <svelte:head> won’t load and execute synchronously when client-side navigating to a page, so any globals it creates etc can’t be accessed immediately

[kaisermann]

(maybe it’s using a regex to find <script> tags and doesn’t ignore them when inside svelte:head)

IIRC the compiler sends every script tag that it finds to the preprocessor, which in turn leads to svelte-preprocess trying to understand that “src” as if it were a component script tag. We need some mechanism to detect if it’s a root script tag or a nested one. I’m also not sure if that’s something that should be done in the preprocessor level.