bevy_asset: don't expect large error in wasm (#24192)

# Objective

- `cargo clippy --target wasm32-unknown-unknown -p bevy_asset --no-deps
-- -D warnings`
- `clippy::result_large_err` is not triggered in wasm
- `ErasedLoadedAsset` is not too big in wasm 🤷 

## Solution

- gate the expect

## Testing

- CI