Break if no diff

[JacobDB]

I'm trying to use this module to only overwrite a file if there's a change. Is there a way to say "if no difference, stop the task" ?

My current gulpfile:

var gulp = require("gulp"),
    json = require("json-file"),

    diff = require("gulp-diff"),

    sass = require("gulp-sass"),
    autoprefixer = require("gulp-autoprefixer"),

    src = "./src",
    dev = "./dev";

gulp.task("default", function() {
    return gulp.src(src + "/assets/styles/all.scss")
        .pipe(sass().on("error", sass.logError))
        .pipe(autoprefixer("last 2 version", "ie 8", "ie 9"))

        .pipe(diff(dev + "/assets/styles"))
        .pipe(diff.reporter()) // if this returns anything, skip gulp.dist

        .pipe(gulp.dest(dev + "/assets/styles"));
});

[JacobDB]

Secondary question: If it's the first time I'm compiling, the dev folder doesn't exist, so it throughs an error. Is there an option i could add to diff() to say "skip this if the folder doesn't exist, rather than throwing an error"