Adding a --validate CLI option

[AVGP]

Simple version of a --validate option for the CLI added by highjacking the -c option code.

Sort-of delivers #72

[ravi]

Can we have this? (please!)

[AVGP]

@ravi You can use my branch (referenced in this pull request) to try it :) I'm waiting for feedback or a merge on this, too

[aseemk]

Whoops, I totally missed this PR, sorry about that! Taking a quick look now.

[ravi]

@AVGP Unfortunately I might have misunderstood your commit... I had hoped for more context for the error message, but it seems to me your change does not provide that.

[ravi]

For my ~ 600 line JSON5 config file, the below is mostly useless as an error report, I am afraid:

/tmp/node_modules/json5/lib/json5.js:54
            throw error;
                  ^
SyntaxError: Expected ']' instead of '{'

[aseemk]

Instead of referencing args[2] in multiple spots, let's add a variable to save it, e.g. cmd after args.

[aseemk]

Also, is this boolean logic right? I thought && takes precedence over ||, so you might need to wrap the -c || --validate check in parentheses.

[aseemk]

Nice work otherwise @AVGP. Thank you for the pull request! =)

[aseemk]

Good point @ravi. So this won't fix that. Please feel free to open a new issue to add line and column number to syntax error messages. Hopefully it won't be too hard for someone to take a stab at.

[ravi]

Created #86 . Thanks.

[jordanbtucker]

Fixed in 35269da