Decode URIs before checking filename against manifest

[Rich-Harris]

Fixes #1501 — fetch('/file with spaces.json') and fetch('/file%20with%20spaces.json') are treated the same way when static/file with spaces.json exists and we're prerendering

Please don't delete this checklist! Before submitting the PR, please make sure you do the following:

• It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs
• This message body should clearly illustrate what problems it solves.
• Ideally, include a test that fails without this PR but passes with it.

Tests

• Run the tests with pnpm test and lint the project with pnpm lint and pnpm check

Changesets

• If your PR makes a change that should be noted in one or more packages' changelogs, generate a changeset by running pnpx changeset and following the prompts. All changesets should be patch until SvelteKit 1.0

[changeset-bot]

🦋 Changeset detected

Latest commit: 75462d2

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@sveltejs/kit	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[netlify]

✔️ Deploy Preview for kit-demo canceled.

🔨 Explore the source changes: 75462d2

🔍 Inspect the deploy log: https://app.netlify.com/sites/kit-demo/deploys/61f2d07dd595510007b581eb

[Mlocik97]

lol, just few days ago I saw PR, where decodeURIComponent was removed from this code.

[benmccann]

Are you sure? I just jumped back several commits in the git history and don't see it:

kit/packages/kit/src/runtime/server/page/load_node.js

Line 104 in f44693a

const filename = resolved.replace(options.paths.assets, '').slice(1);

Please point at the PR if I'm missing it

[Mlocik97]

oh it was similiar code in other file, sorry.