Fix gulp watch stopping on error.

[mariusc23]

Fixes #90. Related to: gulpjs/gulp#259

I think recommending people to not return the gulp stream is not a good idea, because gulp will not know when the task is complete, therefore any tasks that depend on sass being done will not be guaranteed that (think race conditions).

[Keats]

Wouldn't it be more consistent with the other plugins I've seen to use gutil.PluginError instead of log ? It should take care of that

[mariusc23]

That's a good point. I haven't been using gulp that long so I forgot about gutil. I updated the pull request. Let me know what you think.

[Keats]

i think you can just return a new gutil.PluginError looking at other gulp plugins using cb like https://github.com/wearefractal/gulp-coffee/blob/master/index.js#L38

[Snugug]

@Keats Just tested, this.emit('end') is needed.

[ne0-cz]

This breaks my gulp setup - I'm not sure if I should open new issue, continue with discussion here or if I'm just using gulp-sass the wrong way.

The stopping of watch on error was a big issue for me, so I found a workaround:

.pipe(sass().on('error', function(err) {
    sass.logError(err);
    this.emit('end');
}))

This permitted me to have visual bell in console (console.log('\u0007');) on error which also greatly helps my current workflow.

My approach is broken by this commit, since this.emit('end'); in gulpSass.logError function has different this context depending on the way it's called (my way is not working, the usual .pipe(sass().on('error', sass.logError)) works).

I don't really understand javascript that much but since this line is the only usage of magic keyword this in the plugin I feel like this is not way to go - but then again I can't think of any better way since I'm new to the whole gulp/npm scene.