Sequencing tasks with gulp - gulp

Question

I'm a bit stumped with gulp. Based on the docs, in order to get sequential execution, I should be returning the stream from my tasks, so i tried to do the below for my gulpfile. But as best I can tell, there's a race condition. Half the time I get ENOENT, lstat errors, the other half it succeeds, but my deployDir has weird folder names and missing files all over.. Am I missing something? Is there a trick to this?
var gulp = require('gulp'),
filter = require('gulp-filter'),
mainBowerFiles = require('main-bower-files'),
del = require('del'),
inject = require("gulp-inject"),
uglify = require('gulp-uglifyjs');
var config = {
bowerDir: 'src/main/html/bower_components',
cssDir: 'src/main/html/css/lib',
fontsDir: 'src/main/html/fonts/lib',
imgDir: 'src/main/html/img/lib',
jsDir: 'src/main/html/js/lib',
deployDir: 'src/main/resources/html'
};
gulp.task('default', ['clean', 'bowerdeps', 'dev']);
gulp.task('clean', function() {
return del([
config.cssDir,
config.fontsDir,
config.jsDir,
config.deployDir
]);
});
gulp.task('dev', function() {
return gulp
.src(['src/main/html/**', '!src/main/html/{bower_components,bower_components/**}'])
.pipe(gulp.dest(config.deployDir));
});
gulp.task('bowerdeps', function() {
var mainFiles = mainBowerFiles();
if(!mainFiles.length) return; // No files found
var jsFilter = filterByRegex('.js$');
var cssFilter = filterByRegex('.css$');
var fontFilter = filterByRegex('.eot$|.svg$|.ttf$|.woff$');
return gulp
.src(mainFiles)
.pipe(jsFilter)
.pipe(gulp.dest(config.jsDir))
.pipe(jsFilter.restore())
.pipe(cssFilter)
.pipe(gulp.dest(config.cssDir))
.pipe(cssFilter.restore())
.pipe(fontFilter)
.pipe(gulp.dest(config.fontsDir));
});
// Utility Functions
var filterByRegex = function(regex){
return filter(function(file){
return file.path.match(new RegExp(regex));
});
};

Answer 1

Dependencies run always parallel: ['clean', 'bowerdeps', 'dev'].
https://github.com/gulpjs/gulp/blob/master/docs/recipes/running-tasks-in-series.md
You can use run-sequence for sequencing tasks.
Other thing: del doesn't return a stream. Use callback instead:
gulp.task('clean', function(cb) {
del([
config.cssDir,
config.fontsDir,
config.jsDir,
config.deployDir
], cb);
});