Asset loading on the Web produces many 404 errors for `.meta` files

[coreh]

Bevy version

5733d24

What you did

Ran any example that loads assets under WASM / WebGL with:

cargo run -p build-wasm-example -- $EXAMPLE_NAME_HERE && python3 -m http.server --directory examples
/wasm

What went wrong

Got barraged with 404 error messages in the web inspector with the page trying to load .meta files for every asset loaded.

Additional information

• Looks like with Bevy Asset V2 #8624 we now look for .meta files for every asset that we load
• On native this is a non issue, however on the web we do a bunch of requests, which both spam the console with 404 errors and also potentially slow down loading of the files that actually exist

[hymm]

A solution might be for the web asset source to write out a manifest file of the available asset files. This could also be used to solve load_folder not working on the web.

[mockersf]

Adding the 0.12 milestone. I think this should be looked over before the release, it will raise a lot of questions on wasm

[hymm]

Should probably just suppress the error message on wasm for now, until we come up with something better.

[alice-i-cecile]

No PR exists, and the release is imminent. Bumping to 0.13, but I'd nominate this for 0.12.1 as well.

[rparrett]

Adding this info for searchability.

This is also tripping up users who are using trunk or other dev web servers that act in an "SPA" mode where the server doesn't actually serve 404s.

They will see error messages like

/home/redacted/.cargo/registry/src/index.crates.io-6f17d22bba15001f/bevy_asset-0.12.0/src/server/mod.rs:274 Failed to deserialize meta for asset image.png: Failed to deserialize minimal asset meta: SpannedError { code: ExpectedNamedStructLike("AssetMetaMinimal"), position: Position { line: 1, col: 1 } }

Because the web server is just serving the contents of index.html with a status of 200 when a file is missing.

[forbjok]

When uploaded to itch.io, the server the assets are hosted on return 403 instead of 404, and this actually causes the game to completely fail to run.