remove incorrect error check when sending a packet

There's no need for a check if more than protocol.MaxTrackedSentPackets
packets were sent. There are certain situations where we allow (via
SendingAllowed()) sending of more packets, and we shouldn't throw an
error when the session then actually sends these packets.

session_test.go

@@ -1091,7 +1091,7 @@ var _ = Describe("Session", func() {
 		Expect(sess.rttStats.SmoothedRTT()).To(Equal(rtt)) // make sure it worked
 		sess.packer.packetNumberGenerator.next = n + 1
 		// Now, we send a single packet, and expect that it was retransmitted later
-		err := sess.sentPacketHandler.SentPacket(&ackhandler.Packet{
+		sess.sentPacketHandler.SentPacket(&ackhandler.Packet{
 			PacketNumber: n,
 			Length:       1,
 			Frames: []wire.Frame{&wire.StreamFrame{
@@ -1099,7 +1099,6 @@ var _ = Describe("Session", func() {
 			}},
 			EncryptionLevel: protocol.EncryptionForwardSecure,
 		})
-		Expect(err).NotTo(HaveOccurred())
 		go sess.run()
 		defer sess.Close(nil)
 		sess.scheduleSending()