Client sending teleport id of last teleport causes server side exceptions

The bug

The following is based on decompiled version of Minecraft 1.9 using MCP 9.24 beta. All method and class names are the names used in the decompiled version.

The client can send CPacketConfirmTeleport packets with the teleport id it received from the last SPacketPlayerPosLook packet. This way the server tries to teleport the player, however the field net.minecraft.network.NetHandlerPlayServer.field_184362_y is already null which causes NullPointExceptions to be thrown. A client spamming these packets could eventually crash the server because of the exceptions being logged.
The method net.minecraft.network.NetHandlerPlayServer.func_184339_a(CPacketConfirmTeleport) should probably test first if the field net.minecraft.network.NetHandlerPlayServer.field_184362_y is not null.