[Fix] Only throw errors

[esizer]

🤖 Resolves #11378

👋 Introduction

Updates our throws to use custom errors instead of hijacking the response.

🕵️ Details

This had to tweak our error boundary to use Errors instead of Responses. Though, you could get an error response so we have to handle that as well (even though we don't directly use them).

🧪 Testing

1. Bujild pnpm run dev:fresh
2. Confirm explicit throws still render the appropriate error messages
3. Confirm no lint errors

[petertgiles]

Nice! Works well.