Feature Request: Add argument name to MissingArgumentException

[jpozo20]

Hello. First of all, thanks for developing and dedicating time to this awesome library.

I currently need to have the name of the missing argument if required in the exitOverride so I can customize the error that appears on the console. I've been looking through issues, the readme, and parts of the code, and I haven't really found a way to do this.

I'm currently working on a PR to add this little feature, but please do tell me if there is already an existing way of doing it.

[shadowspawn]

Note: you can add to the error displayed in the console, but you can't customise it in exitOverride as it has already been displayed.

The message is one of the properties on CommanderError. So you can parse that for info, but would of course be relying on the message format.

I see PR opened: #2387

[jpozo20]

In my case, I'm overriding the error shown by the library with configureOutput.

As you said, to get the name of the missing argument, one needs to parse the message written by the library to the stderr. But I think that's an implementation detail of the library, and the user shouldn't depend on that since it will break the calling code if the format ever changes. Besides, you wouldn't get the error anyway if you override the output as said above.

Btw, would it be better if we keep the discussion in the PR?