Add null checks to client prefs checks

client.prefs. -> client?.prefs?.

code/game/objects/structures/life_candle.dm

@@ -81,7 +81,7 @@
 		body = new mob_type(T)
 		var/mob/ghostie = mind.get_ghost(TRUE)
 		if(ghostie.client && ghostie.client.prefs)
-			ghostie.client.prefs.copy_to(body)
+			ghostie.client?.prefs?.copy_to(body)
 		mind.transfer_to(body)
 	else
 		body.forceMove(T)

code/game/objects/structures/musician.dm

@@ -67,7 +67,7 @@
 	if((world.time - MUSICIAN_HEARCHECK_MINDELAY) > last_hearcheck)
 		LAZYCLEARLIST(hearing_mobs)
 		for(var/mob/M in get_hearers_in_view(15, source))
-			if(!M.client || !(M.client.prefs.toggles & SOUND_INSTRUMENTS))
+			if(!M.client || !(M.client?.prefs?.toggles & SOUND_INSTRUMENTS))
 				continue
 			LAZYADD(hearing_mobs, M)
 		last_hearcheck = world.time