I know this is something I should know already, but it is stumping me. How can I set a mob to the client?

mob = /mob/player

That is what I would suspect would set it up, but it causes my connection to die and fail. I guess you cannot set a mob at runtime? So, how am I supposed to go about presetting it?
Well, you can define that so the default client mob through world/mob

PS: You are saying that the client's mob is a path, not an existing object, hence the disconnection
In response to GhostAnime
If I cannot use a type path, how would I access it? That doesn't make sense.
In response to Darkjohn66
You need to refer the client's mob to an actual object, otherwise it cannot exist (the client that is). For example:
mob = new/mob/player(X.loc)

Though it is much easier if you define, as mentioned before, the default client mob to to be that path:
mob = /mob/player

(See the entry for world/mob if you are wondering why we don't use new there).
In response to GhostAnime
I see. Thanks!