OSC Parsing Error Handling

[orchetect]

From @dsmurfin:

We get a large number of invalid OSC implementations, so it's quite important to be able to expose errors in parsing to the consumer. Adding this in a backwards compatible manner probably requires adding a new OSCErrorHandlerBlock which provides the host, port and parsing error.

[orchetect]

Absolutely.

In our server/socket classes, OSC parsing errors are only being logged to the console in a debug build. But these errors could definitely be delivered to the consumer, along with the raw packet data that was attempted to be parsed.

1. You're right, a new optional handler closure could be the solution.

   /// Received-message error handler closure used by OSCKit socket classes.
   public typealias OSCErrorHandlerBlock = @Sendable (
       _ packet: Data,
       _ error: OSCDecodeError,
       _ host: String,
       _ port: UInt16
   ) -> Void

2. Then add a _OSCHandlerProtocol protocol requirement:

   var errorHandler: OSCErrorHandlerBlock? { get }

3. Then akin to receiveHandler, add a closure property, nil-defaulted init parameter, and a set handler method to the server/socket classes.

4. Then update OSCUDPServerDelegate to call the error closure instead of logging errors to the console.

Since this is all additive, it should be API-compatible without any code-breaking changes.