Consider using typed throws on methods that always throw ClientError/ServerError

[czechboy0]

Consider using typed throws on methods that always throw ClientError/ServerError.

This will allow adopters to remove an extra } catch { that doesn't have clear purpose.

do {
    _ = try await try await client.getGreeting(input: ...)
} catch as ClientError {
    // This branch is always taken
} catch {
    // This branch is never taken, we always throw ClientError
}

Similar on the server.

With typed throws, we'll be able to do:

do {
    _ = try await try await client.getGreeting(input: ...)
} catch {
    // This branch is always taken and error is statically known to be ClientError
}

[simonjbeaumont]

If we're gonna investigate having user handlers be typed throws we might consider enforcing that any error thrown out of the handler is convertible to HTTP status. We discussed this as an alternative direction when discussing the error handling middleware.