Exit on console-only execution if an error is encountered

If console can not be established (e.g. the node doesn't exist), confetty would drop to interactive.
Address by exiting if the path falls that way.

confluent_client/bin/confetty

@@ -545,6 +545,7 @@ pendingcommand = ""
 if len(shellargs) == 1 and ' ' not in shellargs[0]:  # straight to node console
     consoleonly = True
     do_command("start /nodes/%s/console/session" % shellargs[0], netserver)
+    doexit = True
 elif shellargs:
     command = " ".join(shellargs)
     do_command(command, netserver)