Gulpfile for run watch commands for Gitify (MODX)

Gulpfile.js

'use strict';

console.time('Loading plugins');

var gulp = require('gulp'),
    watch = require('gulp-watch'),    
    shell = require('gulp-shell'),
    tap = require('gulp-tap');

console.timeEnd('Loading plugins');

var path = {
    watch: {
        modx: '_data/**/*.*'
    },    
    modx: {
        root: '.',
        data: '_data/'
    }
};

function modxTaskCreator(type) {
    gulp.task('modx:build:' + type, function () {
        gulp.src(path.modx.data + type) 
            .pipe(shell([
                //'gitify build ' + type + ' --skip-clear-cache'
                'gitify build ' + type
            ], {cwd: path.modx.root}));
        });
}

gulp.task('modx:init', function() {
    gulp.src(path.modx.data + '*')
        .pipe(tap(function (file, t) {            
            modxTaskCreator(file.path.split('/').pop());
        }));
});

gulp.start('modx:init');

gulp.task('modx:build', function() {
    gulp.src(path.modx.data + '*')
        .pipe(tap(function (file, t) {
            gulp.start('modx:build:' + file.path.split('/').pop());
        }));
});

gulp.task('watch', function(){
    watch([path.watch.modx], function(event, cb) {
        var path = event.path.split('/');
        var type = path[path.length - 2];        
        gulp.start('modx:build:' + type);
    });
});

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

package.json

{
    "name": "sitename.com",
    "version": "1.0.0",
    "devDependencies": {
        "gulp": "^3.8.1",
        "gulp-shell": "*",
        "gulp-tap": "*",
        "gulp-watch": "*"
    }
}

run.sh

# examples ans steps for run
# For start you should copy Gulpfile.js and package.json to your MODX root directory. 
# You should have installed Gitify (globbaly, should be available run gitify command from CLI, see documentation of Gitify)

# 1. Install nodejs and npm (here https://nodejs.org/)
# 2. Install gulp with dependencies 
npm install

# 3. Run gulp tasks for build and watch
gulp

При запуске gulp все проходит успешно, стоит изменить какой-либо файл шаблона в _data/templates выходит ошибка
Task 'modx:build:undefined' is not in your gulpfile. В чем причина?