Invalid commands exit without any error messages

[mukkachaitanya]

Description

Use of invalid commands exits the prompt with no output to the stdout.

Steps to Reproduce

For example autolabjs prefs changeserver --type github exits promptly with no output. (github is not a valid server)

Expected behavior:
A proper error message to the stdout.

Actual behavior:
No error message is put to the stdout currently

[prasadtalasila]

There is a PR on caporal.js which fixes part of the problem.