fix(PIClientServer): delete PIEthernet when client_factory returns nullptr

When the custom client_factory() returned nullptr, the incoming
PIEthernet pointer was leaked. Matches existing pattern used in the
max_clients overflow branch.

libs/client_server/piclientserver_server.cpp

@@ -37,6 +37,7 @@ PIClientServer::Server::Server() {
 		auto sc = client_factory();
 		if (!sc) {
 			piCout << "ClientFactory returns nullptr!"_tr("PIClientServer");
+			delete c;
 			return;
 		}
 		sc->createForServer(this, c);