ack emits should allow custom types

Author: nuclearace

Source/SocketAckEmitter.swift

@@ -48,11 +48,18 @@ public final class SocketAckEmitter : NSObject {
 
     /// Call to ack receiving this event.
     ///
+    /// If an error occurs trying to transform `items` into their socket representation, a `SocketClientEvent.error`
+    /// will be emitted. The structure of the error data is `[ackNum, items, theError]`
+    ///
     /// - parameter items: A variable number of items to send when acking.
     public func with(_ items: SocketData...) {
         guard ackNum != -1 else { return }
 
-        socket.emitAck(ackNum, with: items)
+        do {
+            socket.emitAck(ackNum, with: try items.map({ try $0.socketRepresentation() }))
+        } catch let err {
+            socket.handleClientEvent(.error, data: [ackNum, items, err])
+        }
     }
 
     /// Call to ack receiving this event.