Syntax error found by jscs lib is eaten by promise, then silently passes by ending with exit code 0

[jscs-dev]

Syntax error found by jscs lib is eaten by promise, then silently passes by ending with exit code 0

[Krinkle]

@markelog

When a file being checked contains a syntax error (e.g. unexpected end on input), the following is the result of running grunt:

So, for example:

--- src/intro.js
( function ( global ) {

'use strict';

Now, of course, such file should be excluded (which I was I did after finding out why grunt was crashing), but there's lots of syntax errors one could accidentally make that this should catch.

I do run jshint on the project in question, but it wasn't caught because the file was listed in .jshintignore already (so JSHint didn't trip on it), and jscs should (and can) handle invalid syntax without relying on jshint to filter it out first.

The jscs lib catches and rejects the promise, but on the grunt-jscs-checker end we weren't registering a fail handler for the promise, at which point vow throws the error globally.

[markelog]

@Krinkle thank you for the detailed test case!