Fixed exiting with an error in watch mode (#1)

gulpfile.js

@@ -8,6 +8,14 @@ var replace = require('gulp-html-replace');
 var htmlMin = require('gulp-htmlmin');
 var del     = require('del');
 
+var failSafe = false;
+
+function shallow(done) {
+    return function (error) {
+        done(error);
+    };
+}
+
 var paths = new function() {
     this.htmlDir = '.';
     this.html = this.htmlDir + '/*.html';
@@ -34,18 +42,18 @@ var paths = new function() {
     this.lessOut = this.lessDir;
 };
 
-gulp.task('compile-less', function () {
+gulp.task('compile-less', function (done) {
     return gulp.src(paths.less)
-        .pipe(less())
-        .pipe(nano())
+        .pipe(less().on(failSafe ? 'error' : 'none', shallow(done)))
+        .pipe(nano().on(failSafe ? 'error' : 'none', shallow(done)))
         .pipe(rename({
             suffix: '.min'
         }))
         .pipe(gulp.dest(paths.lessOut));
 });
-gulp.task('min-css', function () {
+gulp.task('min-css', function (done) {
     return gulp.src(paths.css)
-        .pipe(nano())
+        .pipe(nano().on(failSafe ? 'error' : 'none', shallow(done)))
         .pipe(rename({
             suffix: '.min'
         }))
@@ -57,9 +65,9 @@ gulp.task('concat-css', ['compile-less', 'min-css'], function () {
         .pipe(gulp.dest(paths.cssOut));
 });
 
-gulp.task('min-js', function() {
+gulp.task('min-js', function (done) {
     return gulp.src(paths.js)
-        .pipe(uglify())
+        .pipe(uglify().on(failSafe ? 'error' : 'none', shallow(done)))
         .pipe(rename({
             suffix: '.min'
         }))
@@ -91,6 +99,7 @@ gulp.task('min-html', ['html-replace'], function () {
 gulp.task('test', ['concat-css', 'concat-js']);
 
 gulp.task('watch', function () {
+    failSafe = true;
     gulp.watch([paths.css, paths.less], ['concat-css']);
     gulp.watch(paths.js, ['concat-js']);
 });