code: function bundle() {
  
      gutil.log('Compiling JS...');
  
      return bundler.bundle()
          .on('error', function (err) {
              gutil.log(err.message);
              browserSync.notify("Browserify Error!");
              this.emit("end");
          })
          .pipe(exorcist('app/js/dist/bundle.js.map'))
          .pipe(source('bundle.js'))
          .pipe(gulp.dest('./app/js/dist'));
  }
docs: On updates recompile bundler.on('update', bundle);