Throw a preemptive exception when sending presence data before connect
Throw a preemptive exception when sending presence data before connect

This prevents a later, less detailed nullref, when attempting to set the CurrentUser's presence data.

This also removes a redundant CurrentUser assignment in the SetGameAsync method, since this will be set later on in the SendStatusAsync method.
Confruggy/Discord.Net,RogueException/Discord.Net,AntiTcb/Discord.Net