It is always possible this is in code I have added to the CLI so feel free to assign it back if that turns out to be the case

Steps: -

• Start wildfly-core
• Start the CLI and connect to the local server, either with -c or connect command.
• Shut down server with Ctrl-C and start again
• Enter command in CLI

Result: -

[standalone@localhost:9990 /] connect
Failed to handle 'connect': java.lang.NullPointerException

Restarting the CLI it is able to connect.