Debug Voting (#9776)

Fixes #9755 by not putting any nulls into the voting list, puts in debug information to find out how this occurred in the first place

code/__HELPERS/unsorted.dm

@@ -4,6 +4,9 @@
  * A large number of misc global procs.
  */
 
+/proc/SAFE_CRASH(var/msg)
+	CRASH(msg)
+
 /proc/Get_Angle(atom/movable/start,atom/movable/end)//For beams.
 	if(!start || !end) return 0
 	var/dy

code/modules/html_interface/voting/voting.dm

@@ -330,7 +330,11 @@ var/global/datum/controller/vote/vote = new()
 		return
 
 	if(ismob(user))
-		user = user:client
+		var/mob/M = user
+		if(M.client)
+			user = M.client
+		else
+			CRASH("The user [M.name] of type [M.type] has been passed as a mob reference without a client to voting.interact()")
 
 	voting |= user
 	interface.show(user)