Seperate Gulp browserify and watchify tasks

gulpfile.js

'use strict';
var gulp = require('gulp');
var browserify = require('browserify');
var watchify = require('watchify');
var source = require('vinyl-source-stream');
var notify = require('gulp-notify');

// Helper functions
function handleErrors(){
  var args = Array.prototype.slice.call(arguments);

  // Send error to notification center with gulp-notify
  notify.onError({
    title: "Compile Error",
    message: "<%= error.message %>"
  }).apply(this, args);

  // Keep gulp from hanging on this task
  this.emit('end');
}


function bundle(args){
  var bundler;
 
  if( args ){
    bundler = browserify('./app/javascripts/main.js', args);
  } else {
    bundler = browserify('./app/javascripts/main.js');
  }
 
  bundler.bundle()
    .on('error', handleErrors)
    .pipe(source('app.js'))
    .pipe(gulp.dest('./dist/'));
 
  return bundler;
}
 
// Tasks
gulp.task('browserify', bundle);
 
gulp.task('watch', function() {
  var bundler = watchify( bundle(watchify.args) );
 
  bundler.on('update', bundle);
 
  return bundler;
});

gulp.task('default', ['watch']);

Note: this still needs to be revised because of a memory leak due to constantly calling browserify. Should just be calling .bundle() instead of browserify each time.