unicode routes with style tag don't load

[luminr]

Describe the bug

Hi. Routes with non-latin character in their names (e.g. あ.svelte) don't compile if they have root-level style tags.

Reproduction

https://stackblitz.com/edit/sveltekit-p8qavo?file=src%2Froutes%2Findex.svelte

Logs

[plugin:vite-plugin-svelte] Failed to execute 'btoa' on 'WorkerGlobalScope': The string to be encoded contains characters outside of the Latin1 range.
/home/projects/sveltekit-p8qavo/src/routes/文.svelte
    at SourceMap.toUrl (file:///home/projects/sveltekit-p8qavo/node_modules/svelte/compiler.mjs:24897:72)
    at dom (file:///home/projects/sveltekit-p8qavo/node_modules/svelte/compiler.mjs:24967:56)
    at Module.compile (file:///home/projects/sveltekit-p8qavo/node_modules/svelte/compiler.mjs:31358:15)
    at compileSvelte2 (file:///home/projects/sveltekit-p8qavo/node_modules/@sveltejs/vite-plugin-svelte/dist/index.js:324:37)
    at async TransformContext.transform (file:///home/projects/sveltekit-p8qavo/node_modules/@sveltejs/vite-plugin-svelte/dist/index.js:1471:27)
    at async Object.transform (/home/projects/sveltekit-p8qavo/node_modules/vite/dist/node/chunks/dep-e0fe87f8.js:42396:30)
    at async doTransform (/home/projects/sveltekit-p8qavo/node_modules/vite/dist/node/chunks/dep-e0fe87f8.js:56801:29

System Info

System:
    OS: Windows 10 10.0.22000
    CPU: -
    Memory: -
  Binaries:
    Node: 17.1.0 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.15 - C:\Program Files\nodejs\yarn.CMD
    npm: 8.1.2 - C:\Program Files\nodejs\npm.CMD
  Browsers:
    Edge: Spartan (44.22000.120.0), Chromium (96.0.1054.62)
    Internet Explorer: 11.0.22000.120
  npmPackages:
    @sveltejs/adapter-auto: next => 1.0.0-next.5
    @sveltejs/adapter-vercel: next => 1.0.0-next.32
    @sveltejs/kit: next => 1.0.0-next.206
    svelte: ^3.44.0 => 3.44.3

Severity

serious, but I can work around it

Additional Information

No response

[benmccann]

The stack trace shows the issue is in node_modules/svelte/compiler.mjs, so this would be a bug in the Svelte compiler

[benmccann]

Seems like it might be referring to this line?

svelte/src/compiler/utils/mapped_code.ts

Line 291 in 4ca2af4

return 'data:application/json;charset=utf-8;base64,' + b64enc(this.toString());

[james-camilleri]

Hey, I've just run into this issue myself with Svelte version 3.46.4, in SvelteKit. Pages with non-Latin characters in the URL blow up as soon as you add a style tag. It seems the btoa function is being used to generate a source map hash, and it doesn't like non ASCII characters. Had a workaround been discovered? Or is there a fix? I suppose this is more likely to be encountered in SvelteKit since the routes are Svelte components that need to be compiled.

[Conduitry]

Duplicate of #6714.