Fix NPE in WrappedGameProfile.getId()

In the current version 3.3.1-SNAPSHOT version of ProtocolLib a NullPointerException is thrown when calling the getId method of WrappedGameProfile using Spigot-1402 (MC 1.7.8).
I'm assuming that was just a typo.
 If I'm wrong and there was another reason, feel free to correct me.