Merge pull request #11852 from Couls/diagonal-movement-runtime-fix

Input subsystem now checks client list for nulls before running keyloop

code/controllers/subsystem/input.dm

@@ -118,6 +118,8 @@ SUBSYSTEM_DEF(input)
 
 /datum/controller/subsystem/input/fire()
 	var/list/clients = GLOB.clients // Let's sing the list cache song
+	if(listclearnulls(clients)) // clear nulls before we run keyloop
+		log_world("Found a null in clients list!")
 	for(var/i in 1 to clients.len)
 		var/client/C = clients[i]
 		C.keyLoop()