Allow loader error to be transformed via handleError

[JakeGinnivan]

When using Prisma or any other ORM a pattern I use often is

const thing = await db.findUnique({ ... })
if (!thing) throw notFound()

It would be great to be able to do something like this:

export function handleError(err: unknown, { request, params, context }: LoaderFunctionArgs | ActionFunctionArgs) {
    if (!request.signal.aborted) {
        if (err instanceof Prisma.PrismaClientKnownRequestError) {
            if (err.code === 'P2025') {
                throw notFound('Not found')
            }
        }
        context.log.error({ err, params }, 'Unhandled error')
    }
}

Or even return the response. It could also open up the idea of specific Errors which have semantic meaning.

The end plan may be for loader middleware to solve this use case, but thought I'd raise it as a separate idea.