Code browser never loads UI for large files, swallows errors

[mootari]

Describe the bug

When trying to serve a large file the /api/registry/file endpoint returns a 413 response (PAYLOAD_TOO_LARGE, see #2332). Due to a lack of explicit error handling the UI remains in a perpetual loading state and fails to render remaining elements like the "Open raw file" button.

Steps:

1. Go to https://npmx.dev/package-code/@types/vscode/v/1.118.0/package.json
2. From the file list select index.d.ts (~720KB)
3. Observe that no error is displayed in the UI and that the "Open raw file" button is never rendered

Additional context

While #2332 is related it is arguably more focused on the backend side. I've filed this issue separately to track the error handling in the UI.

Logs