Why doesn't grunt collect JS files after build?

Question

Yii

I decided to add grunt to Yii2 in order to typeset using less. Did the example from off. guides
https://github.com/samdark/yii2-cookbook/blob/mast...
Gulpfile.js

module.exports = function (grunt) {
    grunt.initConfig({
        less: {
            dev: {
                options: {
                    compress: false,
                    sourceMap: true,
                    outputSourceFiles: true
                },
                files: {
                    "web/css/all.css": "assets/less/all.less"
                }
            },
            prod: {
                options: {
                    compress: true
                },
                files: {
                    "web/css/all.min.css": "assets/less/all.less"
                }
            }
        },
        typescript: {
            base: {
                src: ['assets/ts/*.ts'],
                dest: 'web/js/all.js',
                options: {
                    module: 'amd',
                    sourceMap: true,
                    target: 'es5'
                }
            }
        },
        concat_sourcemap: {
            options: {
                sourcesContent: true
            },
            all: {
                files: {
                    'web/js/all.js': grunt.file.readJSON('assets/js/all.json')
                }
            }
        },
        copy: {
            main: {
                files: [
                    {expand: true, flatten: true, src: ['vendor/bower/bootstrap/fonts/*'], dest: 'web/fonts/', filter: 'isFile'}
                ]
            }
        },
        uglify: {
            options: {
                mangle: false
            },
            lib: {
                files: {
                    'web/js/lib.min.js': 'web/js/lib.js'
                }
            },
            all: {
                files: {
                    'web/js/all.min.js': 'web/js/all.js'
                }
            }
        },
        watch: {
            typescript: {
                files: ['assets/ts/*.ts'],
                tasks: ['typescript', 'uglify:all'],
                options: {
                    livereload: true
                }
            },
            js: {
                files: ['assets/js/**/*.js', 'assets/js/all.json'],
                tasks: ['concat_sourcemap', 'uglify:lib'],
                options: {
                    livereload: true
                }
            },
            less: {
                files: ['assets/less/**/*.less'],
                tasks: ['less'],
                options: {
                    livereload: true
                }
            },
            fonts: {
                files: [
                    'vendor/bower/bootstrap/fonts/*'
                ],
                tasks: ['copy'],
                options: {
                    livereload: true
                }
            }
        }
    });

    // Plugin loading
    grunt.loadNpmTasks('grunt-typescript');
    grunt.loadNpmTasks('grunt-concat-sourcemap');
    grunt.loadNpmTasks('grunt-contrib-watch');
    grunt.loadNpmTasks('grunt-contrib-less');
    grunt.loadNpmTasks('grunt-contrib-uglify');
    grunt.loadNpmTasks('grunt-contrib-copy');

    // Task definition
    grunt.registerTask('build', ['less', 'typescript', 'copy', 'concat_sourcemap', 'uglify']);
    grunt.registerTask('default', ['watch']);
};

all.json

[
  "../../../vendor/bower/jquery/dist/jquery.js",
  "../../../vendor/bower/bootstrap/dist/js/bootstrap.js",
  "../../../vendor/yiisoft/yii2/assets/yii.js",
  "../../../vendor/yiisoft/yii2/assets/yii.validation.js",
  "../../../vendor/yiisoft/yii2/assets/yii.activeForm.js"
]

Actually, the problem is that css files are collected, but js is not, all.js and all.js.map are empty.