Tell the client to exit on configuration file error.

server.c

@@ -193,6 +193,7 @@ error:
 	c = ARRAY_FIRST(&clients);
 
 	server_write_error(c, cause);
+	server_write_client(c, MSG_EXIT, NULL, 0);
 	xfree(cause);
 
 	server_shutdown = 1;